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deps: update esbuild to 0.27.2 #10

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minori wants to merge 5 commits from dependencies/update-esbuild into main
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Dependency Update

Updates esbuild from 0.19.12 to 0.27.2.

Type

devDependencies

Changelog

Changelog

v0.27.2

  • Allow import path specifiers starting with #/ (#4361)

    Previously the specification for package.json disallowed import path specifiers starting with #/, but this restriction has recently been relaxed and support for it is being added across the JavaScript ecosystem. One use case is using it for a wildcard pattern such as mapping #/* to ./src/* (previously you had to use another character such as #_* instead, which was more confusing). There is some more context in nodejs/node#49182.

    This change was contributed by @hybrist.

  • Automatically add the -webkit-mask prefix (#4357, #4358)

    This release automatically adds the -webkit- vendor prefix for the mask CSS shorthand property:

    /* Original code */
main {
  mask: url(x.png) center/5rem no-repeat
}

/* Old output (with --target=chrome110) */
main {
  mask: url(x.png) center/5rem no-repeat;
}

/* New output (with --target=chrome110) */
main {
  -webkit-mask: url(x.png) center/5rem no-repeat;
  mask: url(x.png) center/5rem no-repeat;
}

    This change was contributed by @BPJEnnova.

  • Additional minification of switch statements (#4176, #4359)

    This release contains additional minification patterns for reducing switch statements. Here is an example:

    // Original code
switch (x) {
  case 0:
    foo()
    break
  case 1:
  default:
    bar()
}

// Old output (with --minify)
switch(x){case 0:foo();break;case 1:default:bar()}

// New output (with --minify)
x===0?foo():bar();

  • Forbid using declarations inside switch clauses (#4323)

    This is a rare change to remove something that was previously possible. The Explicit Resource Management proposal introduced using declarations. These were previously allowed inside case and default clauses in switch statements. This had well-defined semantics and was already widely implemented (by V8, SpiderMonkey, TypeScript, esbuild, and others). However, it was considered to be too confusing because of how scope works in switch statements, so it has been removed from the specification. This edge case will now be a syntax error. See tc39/proposal-explicit-resource-management#215 and rbuckton/ecma262#14 for details.

    Here is an example of code that is no longer allowed:

    switch (mode) {
  case 'read':
    using readLock = db.read()
    return readAll(readLock)

  case 'write':
    using writeLock = db.write()
    return writeAll(writeLock)
}

    That code will now have to be modified to look like this instead (note the additional { and } block statements around each case body):

    switch (mode) {
  case 'read': {
    using readLock = db.read()
    return readAll(readLock)
  }
  case 'write': {
    using writeLock = db.write()
    return writeAll(writeLock)
  }
}

    This is not being released in one of esbuild's breaking change releases since this feature hasn't been finalized yet, and esbuild always tracks the current state of the specification (so esbuild's previous behavior was arguably incorrect).

v0.27.1

  • Fix bundler bug with var nested inside if (#4348)

    This release fixes a bug with the bundler that happens when importing an ES module using require (which causes it to be wrapped) and there's a top-level var inside an if statement without being wrapped in a { ... } block (and a few other conditions). The bundling transform needed to hoist these var declarations outside of the lazy ES module wrapper for correctness. See the issue for details.

  • Fix minifier bug with for inside try inside label (#4351)

    This fixes an old regression from version v0.21.4. Some code was introduced to move the label inside the try statement to address a problem with transforming labeled for await loops to avoid the await (the transformation involves converting the for await loop into a for loop and wrapping it in a try statement). However, it introduces problems for cross-compiled JVM code that uses all three of these features heavily. This release restricts this transform to only apply to for loops that esbuild itself generates internally as part of the for await transform. Here is an example of some affected code:

    // Original code
d: {
  e: {
    try {
      while (1) { break d }
    } catch { break e; }
  }
}

// Old output (with --minify)
a:try{e:for(;;)break a}catch{break e}

// New output (with --minify)
a:e:try{for(;;)break a}catch{break e}

  • Inline IIFEs containing a single expression (#4354)

    Previously inlining of IIFEs (immediately-invoked function expressions) only worked if the body contained a single return statement. Now it should also work if the body contains a single expression statement instead:

    // Original code
const foo = () => {
  const cb = () => {
    console.log(x())
  }
  return cb()
}

// Old output (with --minify)
const foo=()=>(()=>{console.log(x())})();

// New output (with --minify)
const foo=()=>{console.log(x())};

  • The minifier now strips empty finally clauses (#4353)

    This improvement means that finally clauses containing dead code can potentially cause the associated try statement to be removed from the output entirely in minified builds:

    // Original code
function foo(callback) {
  if (DEBUG) stack.push(callback.name);
  try {
    callback();
  } finally {
    if (DEBUG) stack.pop();
  }
}

// Old output (with --minify --define:DEBUG=false)
function foo(a){try{a()}finally{}}

// New output (with --minify --define:DEBUG=false)
function foo(a){a()}

  • Allow tree-shaking of the Symbol constructor

    With this release, calling Symbol is now considered to be side-effect free when the argument is known to be a primitive value. This means esbuild can now tree-shake module-level symbol variables:

    // Original code
const a = Symbol('foo')
const b = Symbol(bar)

// Old output (with --tree-shaking=true)
const a = Symbol("foo");
const b = Symbol(bar);

// New output (with --tree-shaking=true)
const b = Symbol(bar);

v0.27.0

This release deliberately contains backwards-incompatible changes. To avoid automatically picking up releases like this, you should either be pinning the exact version of esbuild in your package.json file (recommended) or be using a version range syntax that only accepts patch upgrades such as ^0.26.0 or ~0.26.0. See npm's documentation about semver for more information.

  • Use Uint8Array.fromBase64 if available (#4286)

    With this release, esbuild's binary loader will now use the new Uint8Array.fromBase64 function unless it's unavailable in the configured target environment. If it's unavailable, esbuild's previous code for this will be used as a fallback. Note that this means you may now need to specify target when using this feature with Node (for example --target=node22) unless you're using Node v25+.

  • Update the Go compiler from v1.23.12 to v1.25.4 (#4208, #4311)

    This raises the operating system requirements for running esbuild:

    • Linux: now requires a kernel version of 3.2 or later
    • macOS: now requires macOS 12 (Monterey) or later

v0.26.0

  • Enable trusted publishing (#4281)

    GitHub and npm are recommending that maintainers for packages such as esbuild switch to trusted publishing. With this release, a VM on GitHub will now build and publish all of esbuild's packages to npm instead of me. In theory.

    Unfortunately there isn't really a way to test that this works other than to do it live. So this release is that live test. Hopefully this release is uneventful and is exactly the same as the previous one (well, except for the green provenance attestation checkmark on npm that happens with trusted publishing).

v0.25.12

  • Fix a minification regression with CSS media queries (#4315)

    The previous release introduced support for parsing media queries which unintentionally introduced a regression with the removal of duplicate media rules during minification. Specifically the grammar for @media <media-type> and <media-condition-without-or> { ... } was missing an equality check for the <media-condition-without-or> part, so rules with different suffix clauses in this position would incorrectly compare equal and be deduplicated. This release fixes the regression.

  • Update the list of known JavaScript globals (#4310)

    This release updates esbuild's internal list of known JavaScript globals. These are globals that are known to not have side-effects when the property is accessed. For example, accessing the global Array property is considered to be side-effect free but accessing the global scrollY property can trigger a layout, which is a side-effect. This is used by esbuild's tree-shaking to safely remove unused code that is known to be side-effect free. This update adds the following global properties:

    From ES2017:

    • Atomics
    • SharedArrayBuffer

    From ES2020:

    • BigInt64Array
    • BigUint64Array

    From ES2021:

    • FinalizationRegistry
    • WeakRef

    From ES2025:

    • Float16Array
    • Iterator

    Note that this does not indicate that constructing any of these objects is side-effect free, just that accessing the identifier is side-effect free. For example, this now allows esbuild to tree-shake classes that extend from Iterator:

    // This can now be tree-shaken by esbuild:
class ExampleIterator extends Iterator {}

  • Add support for the new @view-transition CSS rule (#4313)

    With this release, esbuild now has improved support for pretty-printing and minifying the new @view-transition rule (which esbuild was previously unaware of):

    /* Original code */
@view-transition {
  navigation: auto;
  types: check;
}

/* Old output */
@view-transition { navigation: auto; types: check; }

/* New output */
@view-transition {
  navigation: auto;
  types: check;
}

    The new view transition feature provides a mechanism for creating animated transitions between documents in a multi-page app. You can read more about view transition rules here.

    This change was contributed by @yisibl.

  • Trim CSS rules that will never match

    The CSS minifier will now remove rules whose selectors contain :is() and :where() as those selectors will never match. These selectors can currently be automatically generated by esbuild when you give esbuild nonsensical input such as the following:

    /* Original code */
div:before {
  color: green;
  &.foo {
    color: red;
  }
}

/* Old output (with --supported:nesting=false --minify) */
div:before{color:green}:is().foo{color:red}

/* New output (with --supported:nesting=false --minify) */
div:before{color:green}

    This input is nonsensical because CSS nesting is (unfortunately) not supported inside of pseudo-elements such as :before. Currently esbuild generates a rule containing :is() in this case when you tell esbuild to transform nested CSS into non-nested CSS. I think it's reasonable to do that as it sort of helps explain what's going on (or at least indicates that something is wrong in the output). It shouldn't be present in minified code, however, so this release now strips it out.

v0.25.11

  • Add support for with { type: 'bytes' } imports (#4292)

    The import bytes proposal has reached stage 2.7 in the TC39 process, which means that although it isn't quite recommended for implementation, it's generally approved and ready for validation. Furthermore it has already been implemented by Deno and Webpack. So with this release, esbuild will also add support for this. It behaves exactly the same as esbuild's existing binary loader. Here's an example:

    import data from './image.png' with { type: 'bytes' }
const view = new DataView(data.buffer, 0, 24)
const width = view.getInt32(16)
const height = view.getInt32(20)
console.log('size:', width + '\xD7' + height)

  • Lower CSS media query range syntax (#3748, #4293)

    With this release, esbuild will now transform CSS media query range syntax into equivalent syntax using min-/max- prefixes for older browsers. For example, the following CSS:

    @media (640px <= width <= 960px) {
  main {
    display: flex;
  }
}

    will be transformed like this with a target such as --target=chrome100 (or more specifically with --supported:media-range=false if desired):

    @media (min-width: 640px) and (max-width: 960px) {
  main {
    display: flex;
  }
}

v0.25.10

  • Fix a panic in a minification edge case (#4287)

    This release fixes a panic due to a null pointer that could happen when esbuild inlines a doubly-nested identity function and the final result is empty. It was fixed by emitting the value undefined in this case, which avoids the panic. This case must be rare since it hasn't come up until now. Here is an example of code that previously triggered the panic (which only happened when minifying):

    function identity(x) { return x }
identity({ y: identity(123) })

  • Fix @supports nested inside pseudo-element (#4265)

    When transforming nested CSS to non-nested CSS, esbuild is supposed to filter out pseudo-elements such as ::placeholder for correctness. The CSS nesting specification says the following:

    The nesting selector cannot represent pseudo-elements (identical to the behavior of the ':is()' pseudo-class). We’d like to relax this restriction, but need to do so simultaneously for both ':is()' and '&', since they’re intentionally built on the same underlying mechanisms.

    However, it seems like this behavior is different for nested at-rules such as @supports, which do work with pseudo-elements. So this release modifies esbuild's behavior to now take that into account:

    /* Original code */
::placeholder {
  color: red;
  body & { color: green }
  @supports (color: blue) { color: blue }
}

/* Old output (with --supported:nesting=false) */
::placeholder {
  color: red;
}
body :is() {
  color: green;
}
@supports (color: blue) {
   {
    color: blue;
  }
}

/* New output (with --supported:nesting=false) */
::placeholder {
  color: red;
}
body :is() {
  color: green;
}
@supports (color: blue) {
  ::placeholder {
    color: blue;
  }
}

v0.25.9

  • Better support building projects that use Yarn on Windows (#3131, #3663)

    With this release, you can now use esbuild to bundle projects that use Yarn Plug'n'Play on Windows on drives other than the C: drive. The problem was as follows:

    1. Yarn in Plug'n'Play mode on Windows stores its global module cache on the C: drive
    2. Some developers put their projects on the D: drive
    3. Yarn generates relative paths that use ../.. to get from the project directory to the cache directory
    4. Windows-style paths don't support directory traversal between drives via .. (so D:\.. is just D:)
    5. I didn't have access to a Windows machine for testing this edge case

    Yarn works around this edge case by pretending Windows-style paths beginning with C:\ are actually Unix-style paths beginning with /C:/, so the ../.. path segments are able to navigate across drives inside Yarn's implementation. This was broken for a long time in esbuild but I finally got access to a Windows machine and was able to debug and fix this edge case. So you should now be able to bundle these projects with esbuild.

  • Preserve parentheses around function expressions (#4252)

    The V8 JavaScript VM uses parentheses around function expressions as an optimization hint to immediately compile the function. Otherwise the function would be lazily-compiled, which has additional overhead if that function is always called immediately as lazy compilation involves parsing the function twice. You can read V8's blog post about this for more details.

    Previously esbuild did not represent parentheses around functions in the AST so they were lost during compilation. With this change, esbuild will now preserve parentheses around function expressions when they are present in the original source code. This means these optimization hints will not be lost when bundling with esbuild. In addition, esbuild will now automatically add this optimization hint to immediately-invoked function expressions. Here's an example:

    // Original code
const fn0 = () => 0
const fn1 = (() => 1)
console.log(fn0, function() { return fn1() }())

// Old output
const fn0 = () => 0;
const fn1 = () => 1;
console.log(fn0, function() {
  return fn1();
}());

// New output
const fn0 = () => 0;
const fn1 = (() => 1);
console.log(fn0, (function() {
  return fn1();
})());

    Note that you do not want to wrap all function expressions in parentheses. This optimization hint should only be used for functions that are called on initial load. Using this hint for functions that are not called on initial load will unnecessarily delay the initial load. Again, see V8's blog post linked above for details.

  • Update Go from 1.23.10 to 1.23.12 (#4257, #4258)

    This should have no effect on existing code as this version change does not change Go's operating system support. It may remove certain false positive reports (specifically CVE-2025-4674 and CVE-2025-47907) from vulnerability scanners that only detect which version of the Go compiler esbuild uses.

v0.25.8

  • Fix another TypeScript parsing edge case (#4248)

    This fixes a regression with a change in the previous release that tries to more accurately parse TypeScript arrow functions inside the ?: operator. The regression specifically involves parsing an arrow function containing a #private identifier inside the middle of a ?: ternary operator inside a class body. This was fixed by propagating private identifier state into the parser clone used to speculatively parse the arrow function body. Here is an example of some affected code:

    class CachedDict {
  #has = (a: string) => dict.has(a);
  has = window
    ? (word: string): boolean => this.#has(word)
    : this.#has;
}

  • Fix a regression with the parsing of source phase imports

    The change in the previous release to parse source phase imports failed to properly handle the following cases:

    import source from 'bar'
import source from from 'bar'
import source type foo from 'bar'

    Parsing for these cases should now be fixed. The first case was incorrectly treated as a syntax error because esbuild was expecting the second case. And the last case was previously allowed but is now forbidden. TypeScript hasn't added this feature yet so it remains to be seen whether the last case will be allowed, but it's safer to disallow it for now. At least Babel doesn't allow the last case when parsing TypeScript, and Babel was involved with the source phase import specification.

v0.25.7

  • Parse and print JavaScript imports with an explicit phase (#4238)

    This release adds basic syntax support for the defer and source import phases in JavaScript:

    • defer

      This is a stage 3 proposal for an upcoming JavaScript feature that will provide one way to eagerly load but lazily initialize imported modules. The imported module is automatically initialized on first use. Support for this syntax will also be part of the upcoming release of TypeScript 5.9. The syntax looks like this:

      import defer * as foo from "<specifier>";
const bar = await import.defer("<specifier>");

      Note that this feature deliberately cannot be used with the syntax import defer foo from "<specifier>" or import defer { foo } from "<specifier>".

    • source

      This is a stage 3 proposal for an upcoming JavaScript feature that will provide another way to eagerly load but lazily initialize imported modules. The imported module is returned in an uninitialized state. Support for this syntax may or may not be a part of TypeScript 5.9 (see this issue for details). The syntax looks like this:

      import source foo from "<specifier>";
const bar = await import.source("<specifier>");

      Note that this feature deliberately cannot be used with the syntax import defer * as foo from "<specifier>" or import defer { foo } from "<specifier>".

    This change only adds support for this syntax. These imports cannot currently be bundled by esbuild. To use these new features with esbuild's bundler, the imported paths must be external to the bundle and the output format must be set to esm.

  • Support optionally emitting absolute paths instead of relative paths (#338, #2082, #3023)

    This release introduces the --abs-paths= feature which takes a comma-separated list of situations where esbuild should use absolute paths instead of relative paths. There are currently three supported situations: code (comments and string literals), log (log message text and location info), and metafile (the JSON build metadata).

    Using absolute paths instead of relative paths is not the default behavior because it means that the build results are no longer machine-independent (which means builds are no longer reproducible). Absolute paths can be useful when used with certain terminal emulators that allow you to click on absolute paths in the terminal text and/or when esbuild is being automatically invoked from several different directories within the same script.

  • Fix a TypeScript parsing edge case (#4241)

    This release fixes an edge case with parsing an arrow function in TypeScript with a return type that's in the middle of a ?: ternary operator. For example:

    x = a ? (b) : c => d;
y = a ? (b) : c => d : e;

    The : token in the value assigned to x pairs with the ? token, so it's not the start of a return type annotation. However, the first : token in the value assigned to y is the start of a return type annotation because after parsing the arrow function body, it turns out there's another : token that can be used to pair with the ? token. This case is notable as it's the first TypeScript edge case that esbuild has needed a backtracking parser to parse. It has been addressed by a quick hack (cloning the whole parser) as it's a rare edge case and esbuild doesn't otherwise need a backtracking parser. Hopefully this is sufficient and doesn't cause any issues.

  • Inline small constant strings when minifying

    Previously esbuild's minifier didn't inline string constants because strings can be arbitrarily long, and this isn't necessarily a size win if the string is used more than once. Starting with this release, esbuild will now inline string constants when the length of the string is three code units or less. For example:

    // Original code
const foo = 'foo'
console.log({ [foo]: true })

// Old output (with --minify --bundle --format=esm)
var o="foo";console.log({[o]:!0});

// New output (with --minify --bundle --format=esm)
console.log({foo:!0});

    Note that esbuild's constant inlining only happens in very restrictive scenarios to avoid issues with TDZ handling. This change doesn't change when esbuild's constant inlining happens. It only expands the scope of it to include certain string literals in addition to numeric and boolean literals.

v0.25.6

  • Fix a memory leak when cancel() is used on a build context (#4231)

    Calling rebuild() followed by cancel() in rapid succession could previously leak memory. The bundler uses a producer/consumer model internally, and the resource leak was caused by the consumer being termianted while there were still remaining unreceived results from a producer. To avoid the leak, the consumer now waits for all producers to finish before terminating.

  • Support empty :is() and :where() syntax in CSS (#4232)

    Previously using these selectors with esbuild would generate a warning. That warning has been removed in this release for these cases.

  • Improve tree-shaking of try statements in dead code (#4224)

    With this release, esbuild will now remove certain try statements if esbuild considers them to be within dead code (i.e. code that is known to not ever be evaluated). For example:

    // Original code
return 'foo'
try { return 'bar' } catch {}

// Old output (with --minify)
return"foo";try{return"bar"}catch{}

// New output (with --minify)
return"foo";

  • Consider negated bigints to have no side effects

    While esbuild currently considers 1, -1, and 1n to all have no side effects, it didn't previously consider -1n to have no side effects. This is because esbuild does constant folding with numbers but not bigints. However, it meant that unused negative bigint constants were not tree-shaken. With this release, esbuild will now consider these expressions to also be side-effect free:

    // Original code
let a = 1, b = -1, c = 1n, d = -1n

// Old output (with --bundle --minify)
(()=>{var n=-1n;})();

// New output (with --bundle --minify)
(()=>{})();

  • Support a configurable delay in watch mode before rebuilding (#3476, #4178)

    The watch() API now takes a delay option that lets you add a delay (in milliseconds) before rebuilding when a change is detected in watch mode. If you use a tool that regenerates multiple source files very slowly, this should make it more likely that esbuild's watch mode won't generate a broken intermediate build before the successful final build. This option is also available via the CLI using the --watch-delay= flag.

    This should also help avoid confusion about the watch() API's options argument. It was previously empty to allow for future API expansion, which caused some people to think that the documentation was missing. It's no longer empty now that the watch() API has an option.

  • Allow mixed array for entryPoints API option (#4223)

    The TypeScript type definitions now allow you to pass a mixed array of both string literals and object literals to the entryPoints API option, such as ['foo.js', { out: 'lib', in: 'bar.js' }]. This was always possible to do in JavaScript but the TypeScript type definitions were previously too restrictive.

  • Update Go from 1.23.8 to 1.23.10 (#4204, #4207)

    This should have no effect on existing code as this version change does not change Go's operating system support. It may remove certain false positive reports (specifically CVE-2025-4673 and CVE-2025-22874) from vulnerability scanners that only detect which version of the Go compiler esbuild uses.

  • Experimental support for esbuild on OpenHarmony (#4212)

    With this release, esbuild now publishes the @esbuild/openharmony-arm64 npm package for OpenHarmony. It contains a WebAssembly binary instead of a native binary because Go doesn't currently support OpenHarmony. Node does support it, however, so in theory esbuild should now work on OpenHarmony through WebAssembly.

    This change was contributed by @hqzing.

v0.25.5

  • Fix a regression with browser in package.json (#4187)

    The fix to #4144 in version 0.25.3 introduced a regression that caused browser overrides specified in package.json to fail to override relative path names that end in a trailing slash. That behavior change affected the axios@0.30.0 package. This regression has been fixed, and now has test coverage.

  • Add support for certain keywords as TypeScript tuple labels (#4192)

    Previously esbuild could incorrectly fail to parse certain keywords as TypeScript tuple labels that are parsed by the official TypeScript compiler if they were followed by a ? modifier. These labels included function, import, infer, new, readonly, and typeof. With this release, these keywords will now be parsed correctly. Here's an example of some affected code:

    type Foo = [
  value: any,
  readonly?: boolean, // This is now parsed correctly
]

  • Add CSS prefixes for the stretch sizing value (#4184)

    This release adds support for prefixing CSS declarations such as div { width: stretch }. That CSS is now transformed into this depending on what the --target= setting includes:

    div {
  width: -webkit-fill-available;
  width: -moz-available;
  width: stretch;
}

v0.25.4

  • Add simple support for CORS to esbuild's development server (#4125)

    Starting with version 0.25.0, esbuild's development server is no longer configured to serve cross-origin requests. This was a deliberate change to prevent any website you visit from accessing your running esbuild development server. However, this change prevented (by design) certain use cases such as "debugging in production" by having your production website load code from localhost where the esbuild development server is running.

    To enable this use case, esbuild is adding a feature to allow Cross-Origin Resource Sharing (a.k.a. CORS) for simple requests. Specifically, passing your origin to the new cors option will now set the Access-Control-Allow-Origin response header when the request has a matching Origin header. Note that this currently only works for requests that don't send a preflight OPTIONS request, as esbuild's development server doesn't currently support OPTIONS requests.

    Some examples:

    • CLI:

      esbuild --servedir=. --cors-origin=https://example.com

    • JS:

      const ctx = await esbuild.context({})
await ctx.serve({
  servedir: '.',
  cors: {
    origin: 'https://example.com',
  },
})

    • Go:

      ctx, _ := api.Context(api.BuildOptions{})
ctx.Serve(api.ServeOptions{
  Servedir: ".",
  CORS: api.CORSOptions{
    Origin: []string{"https://example.com"},
  },
})

    The special origin * can be used to allow any origin to access esbuild's development server. Note that this means any website you visit will be able to read everything served by esbuild.

  • Pass through invalid URLs in source maps unmodified (#4169)

    This fixes a regression in version 0.25.0 where sources in source maps that form invalid URLs were not being passed through to the output. Version 0.25.0 changed the interpretation of sources from file paths to URLs, which means that URL parsing can now fail. Previously URLs that couldn't be parsed were replaced with the empty string. With this release, invalid URLs in sources should now be passed through unmodified.

  • Handle exports named __proto__ in ES modules (#4162, #4163)

    In JavaScript, the special property name __proto__ sets the prototype when used inside an object literal. Previously esbuild's ESM-to-CommonJS conversion didn't special-case the property name of exports named __proto__ so the exported getter accidentally became the prototype of the object literal. It's unclear what this affects, if anything, but it's better practice to avoid this by using a computed property name in this case.

    This fix was contributed by @magic-akari.

v0.25.3

  • Fix lowered async arrow functions before super() (#4141, #4142)

    This change makes it possible to call an async arrow function in a constructor before calling super() when targeting environments without async support, as long as the function body doesn't reference this. Here's an example (notice the change from this to null):

    // Original code
class Foo extends Object {
  constructor() {
    (async () => await foo())()
    super()
  }
}

// Old output (with --target=es2016)
class Foo extends Object {
  constructor() {
    (() => __async(this, null, function* () {
      return yield foo();
    }))();
    super();
  }
}

// New output (with --target=es2016)
class Foo extends Object {
  constructor() {
    (() => __async(null, null, function* () {
      return yield foo();
    }))();
    super();
  }
}

    Some background: Arrow functions with the async keyword are transformed into generator functions for older language targets such as --target=es2016. Since arrow functions capture this, the generated code forwards this into the body of the generator function. However, JavaScript class syntax forbids using this in a constructor before calling super(), and this forwarding was problematic since previously happened even when the function body doesn't use this. Starting with this release, esbuild will now only forward this if it's used within the function body.

    This fix was contributed by @magic-akari.

  • Fix memory leak with --watch=true (#4131, #4132)

    This release fixes a memory leak with esbuild when --watch=true is used instead of --watch. Previously using --watch=true caused esbuild to continue to use more and more memory for every rebuild, but --watch=true should now behave like --watch and not leak memory.

    This bug happened because esbuild disables the garbage collector when it's not run as a long-lived process for extra speed, but esbuild's checks for which arguments cause esbuild to be a long-lived process weren't updated for the new --watch=true style of boolean command-line flags. This has been an issue since this boolean flag syntax was added in version 0.14.24 in 2022. These checks are unfortunately separate from the regular argument parser because of how esbuild's internals are organized (the command-line interface is exposed as a separate Go API so you can build your own custom esbuild CLI).

    This fix was contributed by @mxschmitt.

  • More concise output for repeated legal comments (#4139)

    Some libraries have many files and also use the same legal comment text in all files. Previously esbuild would copy each legal comment to the output file. Starting with this release, legal comments duplicated across separate files will now be grouped in the output file by unique comment content.

  • Allow a custom host with the development server (#4110)

    With this release, you can now use a custom non-IP host with esbuild's local development server (either with --serve= for the CLI or with the serve() call for the API). This was previously possible, but was intentionally broken in version 0.25.0 to fix a security issue. This change adds the functionality back except that it's now opt-in and only for a single domain name that you provide.

    For example, if you add a mapping in your /etc/hosts file from local.example.com to 127.0.0.1 and then use esbuild --serve=local.example.com:8000, you will now be able to visit http://local.example.com:8000/ in your browser and successfully connect to esbuild's development server (doing that would previously have been blocked by the browser). This should also work with HTTPS if it's enabled (see esbuild's documentation for how to do that).

  • Add a limit to CSS nesting expansion (#4114)

    With this release, esbuild will now fail with an error if there is too much CSS nesting expansion. This can happen when nested CSS is converted to CSS without nesting for older browsers as expanding CSS nesting is inherently exponential due to the resulting combinatorial explosion. The expansion limit is currently hard-coded and cannot be changed, but is extremely unlikely to trigger for real code. It exists to prevent esbuild from using too much time and/or memory. Here's an example:

    a,b{a,b{a,b{a,b{a,b{a,b{a,b{a,b{a,b{a,b{a,b{a,b{a,b{a,b{a,b{a,b{a,b{a,b{a,b{a,b{color:red}}}}}}}}}}}}}}}}}}}}

    Previously, transforming this file with --target=safari1 took 5 seconds and generated 40mb of CSS. Trying to do that will now generate the following error instead:

    ✘ [ERROR] CSS nesting is causing too much expansion

    example.css:1:60:
      1 │ a,b{a,b{a,b{a,b{a,b{a,b{a,b{a,b{a,b{a,b{a,b{a,b{a,b{a,b{a,b{a,b{a,b{a,b{a,b{a,b{color:red}}}}}}}}}}}}}}}}}}}}
        ╵                                                             ^

  CSS nesting expansion was terminated because a rule was generated with 65536 selectors. This limit
  exists to prevent esbuild from using too much time and/or memory. Please change your CSS to use
  fewer levels of nesting.

  • Fix path resolution edge case (#4144)

    This fixes an edge case where esbuild's path resolution algorithm could deviate from node's path resolution algorithm. It involves a confusing situation where a directory shares the same file name as a file (but without the file extension). See the linked issue for specific details. This appears to be a case where esbuild is correctly following node's published resolution algorithm but where node itself is doing something different. Specifically the step LOAD_AS_FILE appears to be skipped when the input ends with ... This release changes esbuild's behavior for this edge case to match node's behavior.

  • Update Go from 1.23.7 to 1.23.8 (#4133, #4134)

    This should have no effect on existing code as this version change does not change Go's operating system support. It may remove certain reports from vulnerability scanners that detect which version of the Go compiler esbuild uses, such as for CVE-2025-22871.

    As a reminder, esbuild's development server is intended for development, not for production, so I do not consider most networking-related vulnerabilities in Go to be vulnerabilities in esbuild. Please do not use esbuild's development server in production.

v0.25.2

  • Support flags in regular expressions for the API (#4121)

    The JavaScript plugin API for esbuild takes JavaScript regular expression objects for the filter option. Internally these are translated into Go regular expressions. However, this translation previously ignored the flags property of the regular expression. With this release, esbuild will now translate JavaScript regular expression flags into Go regular expression flags. Specifically the JavaScript regular expression /\.[jt]sx?$/i is turned into the Go regular expression `(?i)\.[jt]sx?$` internally inside of esbuild's API. This should make it possible to use JavaScript regular expressions with the i flag. Note that JavaScript and Go don't support all of the same regular expression features, so this mapping is only approximate.

  • Fix node-specific annotations for string literal export names (#4100)

    When node instantiates a CommonJS module, it scans the AST to look for names to expose via ESM named exports. This is a heuristic that looks for certain patterns such as exports.NAME = ... or module.exports = { ... }. This behavior is used by esbuild to "annotate" CommonJS code that was converted from ESM with the original ESM export names. For example, when converting the file export let foo, bar from ESM to CommonJS, esbuild appends this to the end of the file:

    // Annotate the CommonJS export names for ESM import in node:
0 && (module.exports = {
  bar,
  foo
});

    However, this feature previously didn't work correctly for export names that are not valid identifiers, which can be constructed using string literal export names. The generated code contained a syntax error. That problem is fixed in this release:

    // Original code
let foo
export { foo as "foo!" }

// Old output (with --format=cjs --platform=node)
...
0 && (module.exports = {
  "foo!"
});

// New output (with --format=cjs --platform=node)
...
0 && (module.exports = {
  "foo!": null
});

  • Basic support for index source maps (#3439, #4109)

    The source map specification has an optional mode called index source maps that makes it easier for tools to create an aggregate JavaScript file by concatenating many smaller JavaScript files with source maps, and then generate an aggregate source map by simply providing the original source maps along with some offset information. My understanding is that this is rarely used in practice. I'm only aware of two uses of it in the wild: ClojureScript and Turbopack.

    This release provides basic support for indexed source maps. However, the implementation has not been tested on a real app (just on very simple test input). If you are using index source maps in a real app, please try this out and report back if anything isn't working for you.

    Note that this is also not a complete implementation. For example, index source maps technically allows nesting source maps to an arbitrary depth, while esbuild's implementation in this release only supports a single level of nesting. It's unclear whether supporting more than one level of nesting is important or not given the lack of available test cases.

    This feature was contributed by @clyfish.

v0.25.1

  • Fix incorrect paths in inline source maps (#4070, #4075, #4105)

    This fixes a regression from version 0.25.0 where esbuild didn't correctly resolve relative paths contained within source maps in inline sourceMappingURL data URLs. The paths were incorrectly being passed through as-is instead of being resolved relative to the source file containing the sourceMappingURL comment, which was due to the data URL not being a file URL. This regression has been fixed, and this case now has test coverage.

  • Fix invalid generated source maps (#4080, #4082, #4104, #4107)

    This release fixes a regression from version 0.24.1 that could cause esbuild to generate invalid source maps. Specifically under certain conditions, esbuild could generate a mapping with an out-of-bounds source index. It was introduced by code that attempted to improve esbuild's handling of "null" entries in source maps (i.e. mappings with a generated position but no original position). This regression has been fixed.

    This fix was contributed by @jridgewell.

  • Fix a regression with non-file source map paths (#4078)

    The format of paths in source maps that aren't in the file namespace was unintentionally changed in version 0.25.0. Path namespaces is an esbuild-specific concept that is optionally available for plugins to use to distinguish paths from file paths and from paths meant for other plugins. Previously the namespace was prepended to the path joined with a : character, but version 0.25.0 unintentionally failed to prepend the namespace. The previous behavior has been restored.

  • Fix a crash with switch optimization (#4088)

    The new code in the previous release to optimize dead code in switch statements accidentally introduced a crash in the edge case where one or more switch case values include a function expression. This is because esbuild now visits the case values first to determine whether any cases are dead code, and then visits the case bodies once the dead code status is known. That triggered some internal asserts that guard against traversing the AST in an unexpected order. This crash has been fixed by changing esbuild to expect the new traversal ordering. Here's an example of affected code:

    switch (x) {
  case '':
    return y.map(z => z.value)
  case y.map(z => z.key).join(','):
    return []
}

  • Update Go from 1.23.5 to 1.23.7 (#4076, #4077)

    This should have no effect on existing code as this version change does not change Go's operating system support. It may remove certain reports from vulnerability scanners that detect which version of the Go compiler esbuild uses.

    This PR was contributed by @MikeWillCook.

v0.25.0

This release deliberately contains backwards-incompatible changes. To avoid automatically picking up releases like this, you should either be pinning the exact version of esbuild in your package.json file (recommended) or be using a version range syntax that only accepts patch upgrades such as ^0.24.0 or ~0.24.0. See npm's documentation about semver for more information.

  • Restrict access to esbuild's development server (GHSA-67mh-4wv8-2f99)

    This change addresses esbuild's first security vulnerability report. Previously esbuild set the Access-Control-Allow-Origin header to * to allow esbuild's development server to be flexible in how it's used for development. However, this allows the websites you visit to make HTTP requests to esbuild's local development server, which gives read-only access to your source code if the website were to fetch your source code's specific URL. You can read more information in the report.

    Starting with this release, CORS will now be disabled, and requests will now be denied if the host does not match the one provided to --serve=. The default host is 0.0.0.0, which refers to all of the IP addresses that represent the local machine (e.g. both 127.0.0.1 and 192.168.0.1). If you want to customize anything about esbuild's development server, you can put a proxy in front of esbuild and modify the incoming and/or outgoing requests.

    In addition, the serve() API call has been changed to return an array of hosts instead of a single host string. This makes it possible to determine all of the hosts that esbuild's development server will accept.

    Thanks to @sapphi-red for reporting this issue.

  • Delete output files when a build fails in watch mode (#3643)

    It has been requested for esbuild to delete files when a build fails in watch mode. Previously esbuild left the old files in place, which could cause people to not immediately realize that the most recent build failed. With this release, esbuild will now delete all output files if a rebuild fails. Fixing the build error and triggering another rebuild will restore all output files again.

  • Fix correctness issues with the CSS nesting transform (#3620, #3877, #3933, #3997, #4005, #4037, #4038)

    This release fixes the following problems:

    • Naive expansion of CSS nesting can result in an exponential blow-up of generated CSS if each nesting level has multiple selectors. Previously esbuild sometimes collapsed individual nesting levels using :is() to limit expansion. However, this collapsing wasn't correct in some cases, so it has been removed to fix correctness issues.

      /* Original code */
.parent {
  > .a,
  > .b1 > .b2 {
    color: red;
  }
}

/* Old output (with --supported:nesting=false) */
.parent > :is(.a, .b1 > .b2) {
  color: red;
}

/* New output (with --supported:nesting=false) */
.parent > .a,
.parent > .b1 > .b2 {
  color: red;
}

      Thanks to @tim-we for working on a fix.

    • The & CSS nesting selector can be repeated multiple times to increase CSS specificity. Previously esbuild ignored this possibility and incorrectly considered && to have the same specificity as &. With this release, this should now work correctly:

      /* Original code (color should be red) */
div {
  && { color: red }
  & { color: blue }
}

/* Old output (with --supported:nesting=false) */
div {
  color: red;
}
div {
  color: blue;
}

/* New output (with --supported:nesting=false) */
div:is(div) {
  color: red;
}
div {
  color: blue;
}

      Thanks to @CPunisher for working on a fix.

    • Previously transforming nested CSS incorrectly removed leading combinators from within pseudoclass selectors such as :where(). This edge case has been fixed and how has test coverage.

      /* Original code */
a b:has(> span) {
  a & {
    color: green;
  }
}

/* Old output (with --supported:nesting=false) */
a :is(a b:has(span)) {
  color: green;
}

/* New output (with --supported:nesting=false) */
a :is(a b:has(> span)) {
  color: green;
}

      This fix was contributed by @NoremacNergfol.

    • The CSS minifier contains logic to remove the & selector when it can be implied, which happens when there is only one and it's the leading token. However, this logic was incorrectly also applied to selector lists inside of pseudo-class selectors such as :where(). With this release, the minifier will now avoid applying this logic in this edge case:

      /* Original code */
.a {
  & .b { color: red }
  :where(& .b) { color: blue }
}

/* Old output (with --minify) */
.a{.b{color:red}:where(.b){color:#00f}}

/* New output (with --minify) */
.a{.b{color:red}:where(& .b){color:#00f}}

  • Fix some correctness issues with source maps (#1745, #3183, #3613, #3982)

    Previously esbuild incorrectly treated source map path references as file paths instead of as URLs. With this release, esbuild will now treat source map path references as URLs. This fixes the following problems with source maps:

    • File names in sourceMappingURL that contained a space previously did not encode the space as %20, which resulted in JavaScript tools (including esbuild) failing to read that path back in when consuming the generated output file. This should now be fixed.

    • Absolute URLs in sourceMappingURL that use the file:// scheme previously attempted to read from a folder called file:. These URLs should now be recognized and parsed correctly.

    • Entries in the sources array in the source map are now treated as URLs instead of file paths. The correct behavior for this is much more clear now that source maps has a formal specification. Many thanks to those who worked on the specification.

  • Fix incorrect package for @esbuild/netbsd-arm64 (#4018)

    Due to a copy+paste typo, the binary published to @esbuild/netbsd-arm64 was not actually for arm64, and didn't run in that environment. This release should fix running esbuild in that environment (NetBSD on 64-bit ARM). Sorry about the mistake.

  • Fix a minification bug with bitwise operators and bigints (#4065)

    This change removes an incorrect assumption in esbuild that all bitwise operators result in a numeric integer. That assumption was correct up until the introduction of bigints in ES2020, but is no longer correct because almost all bitwise operators now operate on both numbers and bigints. Here's an example of the incorrect minification:

    // Original code
if ((a & b) !== 0) found = true

// Old output (with --minify)
a&b&&(found=!0);

// New output (with --minify)
(a&b)!==0&&(found=!0);

  • Fix esbuild incorrectly rejecting valid TypeScript edge case (#4027)

    The following TypeScript code is valid:

    export function open(async?: boolean): void {
  console.log(async as boolean)
}

    Before this version, esbuild would fail to parse this with a syntax error as it expected the token sequence async as ... to be the start of an async arrow function expression async as => .... This edge case should be parsed correctly by esbuild starting with this release.

  • Transform BigInt values into constructor calls when unsupported (#4049)

    Previously esbuild would refuse to compile the BigInt literals (such as 123n) if they are unsupported in the configured target environment (such as with --target=es6). The rationale was that they cannot be polyfilled effectively because they change the behavior of JavaScript's arithmetic operators and JavaScript doesn't have operator overloading.

    However, this prevents using esbuild with certain libraries that would otherwise work if BigInt literals were ignored, such as with old versions of the buffer library before the library fixed support for running in environments without BigInt support. So with this release, esbuild will now turn BigInt literals into BigInt constructor calls (so 123n becomes BigInt(123)) and generate a warning in this case. You can turn off the warning with --log-override:bigint=silent or restore the warning to an error with --log-override:bigint=error if needed.

  • Change how console API dropping works (#4020)

    Previously the --drop:console feature replaced all method calls off of the console global with undefined regardless of how long the property access chain was (so it applied to console.log() and console.log.call(console) and console.log.not.a.method()). However, it was pointed out that this breaks uses of console.log.bind(console). That's also incompatible with Terser's implementation of the feature, which is where this feature originally came from (it does support bind). So with this release, using this feature with esbuild will now only replace one level of method call (unless extended by call or apply) and will replace the method being called with an empty function in complex cases:

    // Original code
const x = console.log('x')
const y = console.log.call(console, 'y')
const z = console.log.bind(console)('z')

// Old output (with --drop-console)
const x = void 0;
const y = void 0;
const z = (void 0)("z");

// New output (with --drop-console)
const x = void 0;
const y = void 0;
const z = (() => {
}).bind(console)("z");

    This should more closely match Terser's existing behavior.

  • Allow BigInt literals as define values

    With this release, you can now use BigInt literals as define values, such as with --define:FOO=123n. Previously trying to do this resulted in a syntax error.

  • Fix a bug with resolve extensions in node_modules (#4053)

    The --resolve-extensions= option lets you specify the order in which to try resolving implicit file extensions. For complicated reasons, esbuild reorders TypeScript file extensions after JavaScript ones inside of node_modules so that JavaScript source code is always preferred to TypeScript source code inside of dependencies. However, this reordering had a bug that could accidentally change the relative order of TypeScript file extensions if one of them was a prefix of the other. That bug has been fixed in this release. You can see the issue for details.

  • Better minification of statically-determined switch cases (#4028)

    With this release, esbuild will now try to trim unused code within switch statements when the test expression and case expressions are primitive literals. This can arise when the test expression is an identifier that is substituted for a primitive literal at compile time. For example:

    // Original code
switch (MODE) {
  case 'dev':
    installDevToolsConsole()
    break
  case 'prod':
    return
  default:
    throw new Error
}

// Old output (with --minify '--define:MODE="prod"')
switch("prod"){case"dev":installDevToolsConsole();break;case"prod":return;default:throw new Error}

// New output (with --minify '--define:MODE="prod"')
return;

  • Emit /* @__KEY__ */ for string literals derived from property names (#4034)

    Property name mangling is an advanced feature that shortens certain property names for better minification (I say "advanced feature" because it's very easy to break your code with it). Sometimes you need to store a property name in a string, such as obj.get('foo') instead of obj.foo. JavaScript minifiers such as esbuild and Terser have a convention where a /* @__KEY__ */ comment before the string makes it behave like a property name. So obj.get(/* @__KEY__ */ 'foo') allows the contents of the string 'foo' to be shortened.

    However, esbuild sometimes itself generates string literals containing property names when transforming code, such as when lowering class fields to ES6 or when transforming TypeScript decorators. Previously esbuild didn't generate its own /* @__KEY__ */ comments in this case, which means that minifying your code by running esbuild again on its own output wouldn't work correctly (this does not affect people that both minify and transform their code in a single step).

    With this release, esbuild will now generate /* @__KEY__ */ comments for property names in generated string literals. To avoid lots of unnecessary output for people that don't use this advanced feature, the generated comments will only be present when the feature is active. If you want to generate the comments but not actually mangle any property names, you can use a flag that has no effect such as --reserve-props=., which tells esbuild to not mangle any property names (but still activates this feature).

  • The text loader now strips the UTF-8 BOM if present (#3935)

    Some software (such as Notepad on Windows) can create text files that start with the three bytes 0xEF 0xBB 0xBF, which is referred to as the "byte order mark". This prefix is intended to be removed before using the text. Previously esbuild's text loader included this byte sequence in the string, which turns into a prefix of \uFEFF in a JavaScript string when decoded from UTF-8. With this release, esbuild's text loader will now remove these bytes when they occur at the start of the file.

  • Omit legal comment output files when empty (#3670)

    Previously configuring esbuild with --legal-comment=external or --legal-comment=linked would always generate a .LEGAL.txt output file even if it was empty. Starting with this release, esbuild will now only do this if the file will be non-empty. This should result in a more organized output directory in some cases.

  • Update Go from 1.23.1 to 1.23.5 (#4056, #4057)

    This should have no effect on existing code as this version change does not change Go's operating system support. It may remove certain reports from vulnerability scanners that detect which version of the Go compiler esbuild uses.

    This PR was contributed by @MikeWillCook.

  • Allow passing a port of 0 to the development server (#3692)

    Unix sockets interpret a port of 0 to mean "pick a random unused port in the ephemeral port range". However, esbuild's default behavior when the port is not specified is to pick the first unused port starting from 8000 and upward. This is more convenient because port 8000 is typically free, so you can for example restart the development server and reload your app in the browser without needing to change the port in the URL. Since esbuild is written in Go (which does not have optional fields like JavaScript), not specifying the port in Go means it defaults to 0, so previously passing a port of 0 to esbuild caused port 8000 to be picked.

    Starting with this release, passing a port of 0 to esbuild when using the CLI or the JS API will now pass port 0 to the OS, which will pick a random ephemeral port. To make this possible, the Port option in the Go API has been changed from uint16 to int (to allow for additional sentinel values) and passing a port of -1 in Go now picks a random port. Both the CLI and JS APIs now remap an explicitly-provided port of 0 into -1 for the internal Go API.

    Another option would have been to change Port in Go from uint16 to *uint16 (Go's closest equivalent of number | undefined). However, that would make the common case of providing an explicit port in Go very awkward as Go doesn't support taking the address of integer constants. This tradeoff isn't worth it as picking a random ephemeral port is a rare use case. So the CLI and JS APIs should now match standard Unix behavior when the port is 0, but you need to use -1 instead with Go API.

  • Minification now avoids inlining constants with direct eval (#4055)

    Direct eval can be used to introduce a new variable like this:

    const variable = false
;(function () {
  eval("var variable = true")
  console.log(variable)
})()

    Previously esbuild inlined variable here (which became false), which changed the behavior of the code. This inlining is now avoided, but please keep in mind that direct eval breaks many assumptions that JavaScript tools hold about normal code (especially when bundling) and I do not recommend using it. There are usually better alternatives that have a more localized impact on your code. You can read more about this here: https://esbuild.github.io/link/direct-eval/

v0.24.2

  • Fix regression with --define and import.meta (#4010, #4012, #4013)

    The previous change in version 0.24.1 to use a more expression-like parser for define values to allow quoted property names introduced a regression that removed the ability to use --define:import.meta=.... Even though import is normally a keyword that can't be used as an identifier, ES modules special-case the import.meta expression to behave like an identifier anyway. This change fixes the regression.

    This fix was contributed by @sapphi-red.

v0.24.1

  • Allow es2024 as a target in tsconfig.json (#4004)

    TypeScript recently added es2024 as a compilation target, so esbuild now supports this in the target field of tsconfig.json files, such as in the following configuration file:

    {
  "compilerOptions": {
    "target": "ES2024"
  }
}

    As a reminder, the only thing that esbuild uses this field for is determining whether or not to use legacy TypeScript behavior for class fields. You can read more in the documentation.

    This fix was contributed by @billyjanitsch.

  • Allow automatic semicolon insertion after get/set

    This change fixes a grammar bug in the parser that incorrectly treated the following code as a syntax error:

    class Foo {
  get
  *x() {}
  set
  *y() {}
}

    The above code will be considered valid starting with this release. This change to esbuild follows a similar change to TypeScript which will allow this syntax starting with TypeScript 5.7.

  • Allow quoted property names in --define and --pure (#4008)

    The define and pure API options now accept identifier expressions containing quoted property names. Previously all identifiers in the identifier expression had to be bare identifiers. This change now makes --define and --pure consistent with --global-name, which already supported quoted property names. For example, the following is now possible:

    // The following code now transforms to "return true;\n"
console.log(esbuild.transformSync(
  `return process.env['SOME-TEST-VAR']`,
  { define: { 'process.env["SOME-TEST-VAR"]': 'true' } },
))

    Note that if you're passing values like this on the command line using esbuild's --define flag, then you'll need to know how to escape quote characters for your shell. You may find esbuild's JavaScript API more ergonomic and portable than writing shell code.

  • Minify empty try/catch/finally blocks (#4003)

    With this release, esbuild will now attempt to minify empty try blocks:

    // Original code
try {} catch { foo() } finally { bar() }

// Old output (with --minify)
try{}catch{foo()}finally{bar()}

// New output (with --minify)
bar();

    This can sometimes expose additional minification opportunities.

  • Include entryPoint metadata for the copy loader (#3985)

    Almost all entry points already include a entryPoint field in the outputs map in esbuild's build metadata. However, this wasn't the case for the copy loader as that loader is a special-case that doesn't behave like other loaders. This release adds the entryPoint field in this case.

  • Source mappings may now contain null entries (#3310, #3878)

    With this change, sources that result in an empty source map may now emit a null source mapping (i.e. one with a generated position but without a source index or original position). This change improves source map accuracy by fixing a problem where minified code from a source without any source mappings could potentially still be associated with a mapping from another source file earlier in the generated output on the same minified line. It manifests as nonsensical files in source mapped stack traces. Now the null mapping "resets" the source map so that any lookups into the minified code without any mappings resolves to null (which appears as the output file in stack traces) instead of the incorrect source file.

    This change shouldn't affect anything in most situations. I'm only mentioning it in the release notes in case it introduces a bug with source mapping. It's part of a work-in-progress future feature that will let you omit certain unimportant files from the generated source map to reduce source map size.

  • Avoid using the parent directory name for determinism (#3998)

    To make generated code more readable, esbuild includes the name of the source file when generating certain variable names within the file. Specifically bundling a CommonJS file generates a variable to store the lazily-evaluated module initializer. However, if a file is named index.js (or with a different extension), esbuild will use the name of the parent directory instead for a better name (since many packages have files all named index.js but have unique directory names).

    This is problematic when the bundle entry point is named index.js and the parent directory name is non-deterministic (e.g. a temporary directory created by a build script). To avoid non-determinism in esbuild's output, esbuild will now use index instead of the parent directory in this case. Specifically this will happen if the parent directory is equal to esbuild's outbase API option, which defaults to the lowest common ancestor of all user-specified entry point paths.

  • Experimental support for esbuild on NetBSD (#3974)

    With this release, esbuild now has a published binary executable for NetBSD in the @esbuild/netbsd-arm64 npm package, and esbuild's installer has been modified to attempt to use it when on NetBSD. Hopefully this makes installing esbuild via npm work on NetBSD. This change was contributed by @bsiegert.

    ⚠️ Note: NetBSD is not one of Node's supported platforms, so installing esbuild may or may not work on NetBSD depending on how Node has been patched. This is not a problem with esbuild. ⚠️

v0.24.0

This release deliberately contains backwards-incompatible changes. To avoid automatically picking up releases like this, you should either be pinning the exact version of esbuild in your package.json file (recommended) or be using a version range syntax that only accepts patch upgrades such as ^0.23.0 or ~0.23.0. See npm's documentation about semver for more information.

  • Drop support for older platforms (#3902)

    This release drops support for the following operating system:

    • macOS 10.15 Catalina

    This is because the Go programming language dropped support for this operating system version in Go 1.23, and this release updates esbuild from Go 1.22 to Go 1.23. Go 1.23 now requires macOS 11 Big Sur or later.

    Note that this only affects the binary esbuild executables that are published to the esbuild npm package. It's still possible to compile esbuild's source code for these older operating systems. If you need to, you can compile esbuild for yourself using an older version of the Go compiler (before Go version 1.23). That might look something like this:

    git clone https://github.com/evanw/esbuild.git
cd esbuild
go build ./cmd/esbuild
./esbuild --version

  • Fix class field decorators in TypeScript if useDefineForClassFields is false (#3913)

    Setting the useDefineForClassFields flag to false in tsconfig.json means class fields use the legacy TypeScript behavior instead of the standard JavaScript behavior. Specifically they use assign semantics instead of define semantics (e.g. setters are triggered) and fields without an initializer are not initialized at all. However, when this legacy behavior is combined with standard JavaScript decorators, TypeScript switches to always initializing all fields, even those without initializers. Previously esbuild incorrectly continued to omit field initializers for this edge case. These field initializers in this case should now be emitted starting with this release.

  • Avoid incorrect cycle warning with tsconfig.json multiple inheritance (#3898)

    TypeScript 5.0 introduced multiple inheritance for tsconfig.json files where extends can be an array of file paths. Previously esbuild would incorrectly treat files encountered more than once when processing separate subtrees of the multiple inheritance hierarchy as an inheritance cycle. With this release, tsconfig.json files containing this edge case should work correctly without generating a warning.

  • Handle Yarn Plug'n'Play stack overflow with tsconfig.json (#3915)

    Previously a tsconfig.json file that extends another file in a package with an exports map could cause a stack overflow when Yarn's Plug'n'Play resolution was active. This edge case should work now starting with this release.

  • Work around more issues with Deno 1.31+ (#3917)

    This version of Deno broke the stdin and stdout properties on command objects for inherited streams, which matters when you run esbuild's Deno module as the entry point (i.e. when import.meta.main is true). Previously esbuild would crash in Deno 1.31+ if you ran esbuild like that. This should be fixed starting with this release.

    This fix was contributed by @Joshix-1.

v0.23.1

  • Allow using the node: import prefix with es* targets (#3821)

    The node: prefix on imports is an alternate way to import built-in node modules. For example, import fs from "fs" can also be written import fs from "node:fs". This only works with certain newer versions of node, so esbuild removes it when you target older versions of node such as with --target=node14 so that your code still works. With the way esbuild's platform-specific feature compatibility table works, this was added by saying that only newer versions of node support this feature. However, that means that a target such as --target=node18,es2022 removes the node: prefix because none of the es* targets are known to support this feature. This release adds the support for the node: flag to esbuild's internal compatibility table for es* to allow you to use compound targets like this:

    // Original code
import fs from 'node:fs'
fs.open

// Old output (with --bundle --format=esm --platform=node --target=node18,es2022)
import fs from "fs";
fs.open;

// New output (with --bundle --format=esm --platform=node --target=node18,es2022)
import fs from "node:fs";
fs.open;

  • Fix a panic when using the CLI with invalid build flags if --analyze is present (#3834)

    Previously esbuild's CLI could crash if it was invoked with flags that aren't valid for a "build" API call and the --analyze flag is present. This was caused by esbuild's internals attempting to add a Go plugin (which is how --analyze is implemented) to a null build object. The panic has been fixed in this release.

  • Fix incorrect location of certain error messages (#3845)

    This release fixes a regression that caused certain errors relating to variable declarations to be reported at an incorrect location. The regression was introduced in version 0.18.7 of esbuild.

  • Print comments before case clauses in switch statements (#3838)

    With this release, esbuild will attempt to print comments that come before case clauses in switch statements. This is similar to what esbuild already does for comments inside of certain types of expressions. Note that these types of comments are not printed if minification is enabled (specifically whitespace minification).

  • Fix a memory leak with pluginData (#3825)

    With this release, the build context's internal pluginData cache will now be cleared when starting a new build. This should fix a leak of memory from plugins that return pluginData objects from onResolve and/or onLoad callbacks.

v0.23.0

This release deliberately contains backwards-incompatible changes. To avoid automatically picking up releases like this, you should either be pinning the exact version of esbuild in your package.json file (recommended) or be using a version range syntax that only accepts patch upgrades such as ^0.22.0 or ~0.22.0. See npm's documentation about semver for more information.

  • Revert the recent change to avoid bundling dependencies for node (#3819)

    This release reverts the recent change in version 0.22.0 that made --packages=external the default behavior with --platform=node. The default is now back to --packages=bundle.

    I've just been made aware that Amazon doesn't pin their dependencies in their "AWS CDK" product, which means that whenever esbuild publishes a new release, many people (potentially everyone?) using their SDK around the world instantly starts using it without Amazon checking that it works first. This change in version 0.22.0 happened to break their SDK. I'm amazed that things haven't broken before this point. This revert attempts to avoid these problems for Amazon's customers. Hopefully Amazon will pin their dependencies in the future.

    In addition, this is probably a sign that esbuild is used widely enough that it now needs to switch to a more complicated release model. I may have esbuild use a beta channel model for further development.

  • Fix preserving collapsed JSX whitespace (#3818)

    When transformed, certain whitespace inside JSX elements is ignored completely if it collapses to an empty string. However, the whitespace should only be ignored if the JSX is being transformed, not if it's being preserved. This release fixes a bug where esbuild was previously incorrectly ignoring collapsed whitespace with --jsx=preserve. Here is an example:

    // Original code
<Foo>
  <Bar />
</Foo>

// Old output (with --jsx=preserve)
<Foo><Bar /></Foo>;

// New output (with --jsx=preserve)
<Foo>
  <Bar />
</Foo>;

v0.22.0

This release deliberately contains backwards-incompatible changes. To avoid automatically picking up releases like this, you should either be pinning the exact version of esbuild in your package.json file (recommended) or be using a version range syntax that only accepts patch upgrades such as ^0.21.0 or ~0.21.0. See npm's documentation about semver for more information.

  • Omit packages from bundles by default when targeting node (#1874, #2830, #2846, #2915, #3145, #3294, #3323, #3582, #3809, #3815)

    This breaking change is an experiment. People are commonly confused when using esbuild to bundle code for node (i.e. for --platform=node) because some packages may not be intended for bundlers, and may use node-specific features that don't work with a bundler. Even though esbuild's "getting started" instructions say to use --packages=external to work around this problem, many people don't read the documentation and don't do this, and are then confused when it doesn't work. So arguably this is a bad default behavior for esbuild to have if people keep tripping over this.

    With this release, esbuild will now omit packages from the bundle by default when the platform is node (i.e. the previous behavior of --packages=external is now the default in this case). Note that your dependencies must now be present on the file system when your bundle is run. If you don't want this behavior, you can do --packages=bundle to allow packages to be included in the bundle (i.e. the previous default behavior). Note that --packages=bundle doesn't mean all packages are bundled, just that packages are allowed to be bundled. You can still exclude individual packages from the bundle using --external: even when --packages=bundle is present.

    The --packages= setting considers all import paths that "look like" package imports in the original source code to be package imports. Specifically import paths that don't start with a path segment of / or . or .. are considered to be package imports. The only two exceptions to this rule are subpath imports (which start with a # character) and TypeScript path remappings via paths and/or baseUrl in tsconfig.json (which are applied first).

  • Drop support for older platforms (#3802)

    This release drops support for the following operating systems:

    • Windows 7
    • Windows 8
    • Windows Server 2008
    • Windows Server 2012

    This is because the Go programming language dropped support for these operating system versions in Go 1.21, and this release updates esbuild from Go 1.20 to Go 1.22.

    Note that this only affects the binary esbuild executables that are published to the esbuild npm package. It's still possible to compile esbuild's source code for these older operating systems. If you need to, you can compile esbuild for yourself using an older version of the Go compiler (before Go version 1.21). That might look something like this:

    git clone https://github.com/evanw/esbuild.git
cd esbuild
go build ./cmd/esbuild
./esbuild.exe --version

    In addition, this release increases the minimum required node version for esbuild's JavaScript API from node 12 to node 18. Node 18 is the oldest version of node that is still being supported (see node's release schedule for more information). This increase is because of an incompatibility between the JavaScript that the Go compiler generates for the esbuild-wasm package and versions of node before node 17.4 (specifically the crypto.getRandomValues function).

  • Update await using behavior to match TypeScript

    TypeScript 5.5 subtly changes the way await using behaves. This release updates esbuild to match these changes in TypeScript. You can read more about these changes in microsoft/TypeScript#58624.

  • Allow es2024 as a target environment

    The ECMAScript 2024 specification was just approved, so it has been added to esbuild as a possible compilation target. You can read more about the features that it adds here: https://2ality.com/2024/06/ecmascript-2024.html. The only addition that's relevant for esbuild is the regular expression /v flag. With --target=es2024, regular expressions that use the /v flag will now be passed through untransformed instead of being transformed into a call to new RegExp.

  • Publish binaries for OpenBSD on 64-bit ARM (#3665, #3674)

    With this release, you should now be able to install the esbuild npm package in OpenBSD on 64-bit ARM, such as on an Apple device with an M1 chip.

    This was contributed by @ikmckenz.

  • Publish binaries for WASI (WebAssembly System Interface) preview 1 (#3300, #3779)

    The upcoming WASI (WebAssembly System Interface) standard is going to be a way to run WebAssembly outside of a JavaScript host environment. In this scenario you only need a .wasm file without any supporting JavaScript code. Instead of JavaScript providing the APIs for the host environment, the WASI standard specifies a "system interface" that WebAssembly code can access directly (e.g. for file system access).

    Development versions of the WASI specification are being released using preview numbers. The people behind WASI are currently working on preview 2 but the Go compiler has released support for preview 1, which from what I understand is now considered an unsupported legacy release. However, some people have requested that esbuild publish binary executables that support WASI preview 1 so they can experiment with them.

    This release publishes esbuild precompiled for WASI preview 1 to the @esbuild/wasi-preview1 package on npm (specifically the file @esbuild/wasi-preview1/esbuild.wasm). This binary executable has not been tested and won't be officially supported, as it's for an old preview release of a specification that has since moved in another direction. If it works for you, great! If not, then you'll likely have to wait for the ecosystem to evolve before using esbuild with WASI. For example, it sounds like perhaps WASI preview 1 doesn't include support for opening network sockets so esbuild's local development server is unlikely to work with WASI preview 1.

  • Warn about onResolve plugins not setting a path (#3790)

    Plugins that return values from onResolve without resolving the path (i.e. without setting either path or external: true) will now cause a warning. This is because esbuild only uses return values from onResolve if it successfully resolves the path, and it's not good for invalid input to be silently ignored.

  • Add a new Go API for running the CLI with plugins (#3539)

    With esbuild's Go API, you can now call cli.RunWithPlugins(args, plugins) to pass an array of esbuild plugins to be used during the build process. This allows you to create a CLI that behaves similarly to esbuild's CLI but with additional Go plugins enabled.

    This was contributed by @edewit.

v0.21.5

  • Fix Symbol.metadata on classes without a class decorator (#3781)

    This release fixes a bug with esbuild's support for the decorator metadata proposal. Previously esbuild only added the Symbol.metadata property to decorated classes if there was a decorator on the class element itself. However, the proposal says that the Symbol.metadata property should be present on all classes that have any decorators at all, not just those with a decorator on the class element itself.

  • Allow unknown import attributes to be used with the copy loader (#3792)

    Import attributes (the with keyword on import statements) are allowed to alter how that path is loaded. For example, esbuild cannot assume that it knows how to load ./bagel.js as type bagel:

    // This is an error with "--bundle" without also using "--external:./bagel.js"
import tasty from "./bagel.js" with { type: "bagel" }

    Because of that, bundling this code with esbuild is an error unless the file ./bagel.js is external to the bundle (such as with --bundle --external:./bagel.js).

    However, there is an additional case where it's ok for esbuild to allow this: if the file is loaded using the copy loader. That's because the copy loader behaves similarly to --external in that the file is left external to the bundle. The difference is that the copy loader copies the file into the output folder and rewrites the import path while --external doesn't. That means the following will now work with the copy loader (such as with --bundle --loader:.bagel=copy):

    // This is no longer an error with "--bundle" and "--loader:.bagel=copy"
import tasty from "./tasty.bagel" with { type: "bagel" }

  • Support import attributes with glob-style imports (#3797)

    This release adds support for import attributes (the with option) to glob-style imports (dynamic imports with certain string literal patterns as paths). These imports previously didn't support import attributes due to an oversight. So code like this will now work correctly:

    async function loadLocale(locale: string): Locale {
  const data = await import(`./locales/${locale}.data`, { with: { type: 'json' } })
  return unpackLocale(locale, data)
}

    Previously this didn't work even though esbuild normally supports forcing the JSON loader using an import attribute. Attempting to do this used to result in the following error:

    ✘ [ERROR] No loader is configured for ".data" files: locales/en-US.data

    example.ts:2:28:
      2 │   const data = await import(`./locales/${locale}.data`, { with: { type: 'json' } })
        ╵                             ~~~~~~~~~~~~~~~~~~~~~~~~~~

    In addition, this change means plugins can now access the contents of with for glob-style imports.

  • Support ${configDir} in tsconfig.json files (#3782)

    This adds support for a new feature from the upcoming TypeScript 5.5 release. The character sequence ${configDir} is now respected at the start of baseUrl and paths values, which are used by esbuild during bundling to correctly map import paths to file system paths. This feature lets base tsconfig.json files specified via extends refer to the directory of the top-level tsconfig.json file. Here is an example:

    {
  "compilerOptions": {
    "paths": {
      "js/*": ["${configDir}/dist/js/*"]
    }
  }
}

    You can read more in TypeScript's blog post about their upcoming 5.5 release. Note that this feature does not make use of template literals (you need to use "${configDir}/dist/js/*" not `${configDir}/dist/js/*`). The syntax for tsconfig.json is still just JSON with comments, and JSON syntax does not allow template literals. This feature only recognizes ${configDir} in strings for certain path-like properties, and only at the beginning of the string.

  • Fix internal error with --supported:object-accessors=false (#3794)

    This release fixes a regression in 0.21.0 where some code that was added to esbuild's internal runtime library of helper functions for JavaScript decorators fails to parse when you configure esbuild with --supported:object-accessors=false. The reason is that esbuild introduced code that does { get [name]() {} } which uses both the object-extensions feature for the [name] and the object-accessors feature for the get, but esbuild was incorrectly only checking for object-extensions and not for object-accessors. Additional tests have been added to avoid this type of issue in the future. A workaround for this issue in earlier releases is to also add --supported:object-extensions=false.

v0.21.4

  • Update support for import assertions and import attributes in node (#3778)

    Import assertions (the assert keyword) have been removed from node starting in v22.0.0. So esbuild will now strip them and generate a warning with --target=node22 or above:

    ▲ [WARNING] The "assert" keyword is not supported in the configured target environment ("node22") [assert-to-with]

    example.mjs:1:40:
      1 │ import json from "esbuild/package.json" assert { type: "json" }
        │                                         ~~~~~~
        ╵                                         with

  Did you mean to use "with" instead of "assert"?

    Import attributes (the with keyword) have been backported to node 18 starting in v18.20.0. So esbuild will no longer strip them with --target=node18.N if N is 20 or greater.

  • Fix for await transform when a label is present

    This release fixes a bug where the for await transform, which wraps the loop in a try statement, previously failed to also move the loop's label into the try statement. This bug only affects code that uses both of these features in combination. Here's an example of some affected code:

    // Original code
async function test() {
  outer: for await (const x of [Promise.resolve([0, 1])]) {
    for (const y of x) if (y) break outer
    throw 'fail'
  }
}

// Old output (with --target=es6)
function test() {
  return __async(this, null, function* () {
    outer: try {
      for (var iter = __forAwait([Promise.resolve([0, 1])]), more, temp, error; more = !(temp = yield iter.next()).done; more = false) {
        const x = temp.value;
        for (const y of x) if (y) break outer;
        throw "fail";
      }
    } catch (temp) {
      error = [temp];
    } finally {
      try {
        more && (temp = iter.return) && (yield temp.call(iter));
      } finally {
        if (error)
          throw error[0];
      }
    }
  });
}

// New output (with --target=es6)
function test() {
  return __async(this, null, function* () {
    try {
      outer: for (var iter = __forAwait([Promise.resolve([0, 1])]), more, temp, error; more = !(temp = yield iter.next()).done; more = false) {
        const x = temp.value;
        for (const y of x) if (y) break outer;
        throw "fail";
      }
    } catch (temp) {
      error = [temp];
    } finally {
      try {
        more && (temp = iter.return) && (yield temp.call(iter));
      } finally {
        if (error)
          throw error[0];
      }
    }
  });
}

  • Do additional constant folding after cross-module enum inlining (#3416, #3425)

    This release adds a few more cases where esbuild does constant folding after cross-module enum inlining.

    // Original code: enum.ts
export enum Platform {
  WINDOWS = 'windows',
  MACOS = 'macos',
  LINUX = 'linux',
}

// Original code: main.ts
import { Platform } from './enum';
declare const PLATFORM: string;
export function logPlatform() {
  if (PLATFORM == Platform.WINDOWS) console.log('Windows');
  else if (PLATFORM == Platform.MACOS) console.log('macOS');
  else if (PLATFORM == Platform.LINUX) console.log('Linux');
  else console.log('Other');
}

// Old output (with --bundle '--define:PLATFORM="macos"' --minify --format=esm)
function n(){"windows"=="macos"?console.log("Windows"):"macos"=="macos"?console.log("macOS"):"linux"=="macos"?console.log("Linux"):console.log("Other")}export{n as logPlatform};

// New output (with --bundle '--define:PLATFORM="macos"' --minify --format=esm)
function n(){console.log("macOS")}export{n as logPlatform};

  • Pass import attributes to on-resolve plugins (#3384, #3639, #3646)

    With this release, on-resolve plugins will now have access to the import attributes on the import via the with property of the arguments object. This mirrors the with property of the arguments object that's already passed to on-load plugins. In addition, you can now pass with to the resolve() API call which will then forward that value on to all relevant plugins. Here's an example of a plugin that can now be written:

    const examplePlugin = {
  name: 'Example plugin',
  setup(build) {
    build.onResolve({ filter: /.*/ }, args => {
      if (args.with.type === 'external')
        return { external: true }
    })
  }
}

require('esbuild').build({
  stdin: {
    contents: `
      import foo from "./foo" with { type: "external" }
      foo()
    `,
  },
  bundle: true,
  format: 'esm',
  write: false,
  plugins: [examplePlugin],
}).then(result => {
  console.log(result.outputFiles[0].text)
})

  • Formatting support for the @position-try rule (#3773)

    Chrome shipped this new CSS at-rule in version 125 as part of the CSS anchor positioning API. With this release, esbuild now knows to expect a declaration list inside of the @position-try body block and will format it appropriately.

  • Always allow internal string import and export aliases (#3343)

    Import and export names can be string literals in ES2022+. Previously esbuild forbid any usage of these aliases when the target was below ES2022. Starting with this release, esbuild will only forbid such usage when the alias would otherwise end up in output as a string literal. String literal aliases that are only used internally in the bundle and are "compiled away" are no longer errors. This makes it possible to use string literal aliases with esbuild's inject feature even when the target is earlier than ES2022.

v0.21.3

  • Implement the decorator metadata proposal (#3760)

    This release implements the decorator metadata proposal, which is a sub-proposal of the decorators proposal. Microsoft shipped the decorators proposal in TypeScript 5.0 and the decorator metadata proposal in TypeScript 5.2, so it's important that esbuild also supports both of these features. Here's a quick example:

    // Shim the "Symbol.metadata" symbol
Symbol.metadata ??= Symbol('Symbol.metadata')

const track = (_, context) => {
  (context.metadata.names ||= []).push(context.name)
}

class Foo {
  @track foo = 1
  @track bar = 2
}

// Prints ["foo", "bar"]
console.log(Foo[Symbol.metadata].names)

    ⚠️ WARNING ⚠️

    This proposal has been marked as "stage 3" which means "recommended for implementation". However, it's still a work in progress and isn't a part of JavaScript yet, so keep in mind that any code that uses JavaScript decorator metadata may need to be updated as the feature continues to evolve. If/when that happens, I will update esbuild's implementation to match the specification. I will not be supporting old versions of the specification.

  • Fix bundled decorators in derived classes (#3768)

    In certain cases, bundling code that uses decorators in a derived class with a class body that references its own class name could previously generate code that crashes at run-time due to an incorrect variable name. This problem has been fixed. Here is an example of code that was compiled incorrectly before this fix:

    class Foo extends Object {
  @(x => x) foo() {
    return Foo
  }
}
console.log(new Foo().foo())

  • Fix tsconfig.json files inside symlinked directories (#3767)

    This release fixes an issue with a scenario involving a tsconfig.json file that extends another file from within a symlinked directory that uses the paths feature. In that case, the implicit baseURL value should be based on the real path (i.e. after expanding all symbolic links) instead of the original path. This was already done for other files that esbuild resolves but was not yet done for tsconfig.json because it's special-cased (the regular path resolver can't be used because the information inside tsconfig.json is involved in path resolution). Note that this fix no longer applies if the --preserve-symlinks setting is enabled.

v0.21.2

  • Correct this in field and accessor decorators (#3761)

    This release changes the value of this in initializers for class field and accessor decorators from the module-level this value to the appropriate this value for the decorated element (either the class or the instance). It was previously incorrect due to lack of test coverage. Here's an example of a decorator that doesn't work without this change:

    const dec = () => function() { this.bar = true }
class Foo { @dec static foo }
console.log(Foo.bar) // Should be "true"

  • Allow es2023 as a target environment (#3762)

    TypeScript recently added es2023 as a compilation target, so esbuild now supports this too. There is no difference between a target of es2022 and es2023 as far as esbuild is concerned since the 2023 edition of JavaScript doesn't introduce any new syntax features.

v0.21.1

  • Fix a regression with --keep-names (#3756)

    The previous release introduced a regression with the --keep-names setting and object literals with get/set accessor methods, in which case the generated code contained syntax errors. This release fixes the regression:

    // Original code
x = { get y() {} }

// Output from version 0.21.0 (with --keep-names)
x = { get y: /* @__PURE__ */ __name(function() {
}, "y") };

// Output from this version (with --keep-names)
x = { get y() {
} };

v0.21.0

This release doesn't contain any deliberately-breaking changes. However, it contains a very complex new feature and while all of esbuild's tests pass, I would not be surprised if an important edge case turns out to be broken. So I'm releasing this as a breaking change release to avoid causing any trouble. As usual, make sure to test your code when you upgrade.

  • Implement the JavaScript decorators proposal (#104)

    With this release, esbuild now contains an implementation of the upcoming JavaScript decorators proposal. This is the same feature that shipped in TypeScript 5.0 and has been highly-requested on esbuild's issue tracker. You can read more about them in that blog post and in this other (now slightly outdated) extensive blog post here: https://2ality.com/2022/10/javascript-decorators.html. Here's a quick example:

    const log = (fn, context) => function() {
  console.log(`before ${context.name}`)
  const it = fn.apply(this, arguments)
  console.log(`after ${context.name}`)
  return it
}

class Foo {
  @log static foo() {
    console.log('in foo')
  }
}

// Logs "before foo", "in foo", "after foo"
Foo.foo()

    Note that this feature is different than the existing "TypeScript experimental decorators" feature that esbuild already implements. It uses similar syntax but behaves very differently, and the two are not compatible (although it's sometimes possible to write decorators that work with both). TypeScript experimental decorators will still be supported by esbuild going forward as they have been around for a long time, are very widely used, and let you do certain things that are not possible with JavaScript decorators (such as decorating function parameters). By default esbuild will parse and transform JavaScript decorators, but you can tell esbuild to parse and transform TypeScript experimental decorators instead by setting "experimentalDecorators": true in your tsconfig.json file.

    Probably at least half of the work for this feature went into creating a test suite that exercises many of the proposal's edge cases: https://github.com/evanw/decorator-tests. It has given me a reasonable level of confidence that esbuild's initial implementation is acceptable. However, I don't have access to a significant sample of real code that uses JavaScript decorators. If you're currently using JavaScript decorators in a real code base, please try out esbuild's implementation and let me know if anything seems off.

    ⚠️ WARNING ⚠️

    This proposal has been in the works for a very long time (work began around 10 years ago in 2014) and it is finally getting close to becoming part of the JavaScript language. However, it's still a work in progress and isn't a part of JavaScript yet, so keep in mind that any code that uses JavaScript decorators may need to be updated as the feature continues to evolve. The decorators proposal is pretty close to its final form but it can and likely will undergo some small behavioral adjustments before it ends up becoming a part of the standard. If/when that happens, I will update esbuild's implementation to match the specification. I will not be supporting old versions of the specification.

  • Optimize the generated code for private methods

    Previously when lowering private methods for old browsers, esbuild would generate one WeakSet for each private method. This mirrors similar logic for generating one WeakSet for each private field. Using a separate WeakMap for private fields is necessary as their assignment can be observable:

    let it
class Bar {
  constructor() {
    it = this
  }
}
class Foo extends Bar {
  #x = 1
  #y = null.foo
  static check() {
    console.log(#x in it, #y in it)
  }
}
try { new Foo } catch {}
Foo.check()

    This prints true false because this partially-initialized instance has #x but not #y. In other words, it's not true that all class instances will always have all of their private fields. However, the assignment of private methods to a class instance is not observable. In other words, it's true that all class instances will always have all of their private methods. This means esbuild can lower private methods into code where all methods share a single WeakSet, which is smaller, faster, and uses less memory. Other JavaScript processing tools such as the TypeScript compiler already make this optimization. Here's what this change looks like:

    // Original code
class Foo {
  #x() { return this.#x() }
  #y() { return this.#y() }
  #z() { return this.#z() }
}

// Old output (--supported:class-private-method=false)
var _x, x_fn, _y, y_fn, _z, z_fn;
class Foo {
  constructor() {
    __privateAdd(this, _x);
    __privateAdd(this, _y);
    __privateAdd(this, _z);
  }
}
_x = new WeakSet();
x_fn = function() {
  return __privateMethod(this, _x, x_fn).call(this);
};
_y = new WeakSet();
y_fn = function() {
  return __privateMethod(this, _y, y_fn).call(this);
};
_z = new WeakSet();
z_fn = function() {
  return __privateMethod(this, _z, z_fn).call(this);
};

// New output (--supported:class-private-method=false)
var _Foo_instances, x_fn, y_fn, z_fn;
class Foo {
  constructor() {
    __privateAdd(this, _Foo_instances);
  }
}
_Foo_instances = new WeakSet();
x_fn = function() {
  return __privateMethod(this, _Foo_instances, x_fn).call(this);
};
y_fn = function() {
  return __privateMethod(this, _Foo_instances, y_fn).call(this);
};
z_fn = function() {
  return __privateMethod(this, _Foo_instances, z_fn).call(this);
};

  • Fix an obscure bug with lowering class members with computed property keys

    When class members that use newer syntax features are transformed for older target environments, they sometimes need to be relocated. However, care must be taken to not reorder any side effects caused by computed property keys. For example, the following code must evaluate a() then b() then c():

    class Foo {
  [a()]() {}
  [b()];
  static { c() }
}

    Previously esbuild did this by shifting the computed property key forward to the next spot in the evaluation order. Classes evaluate all computed keys first and then all static class elements, so if the last computed key needs to be shifted, esbuild previously inserted a static block at start of the class body, ensuring it came before all other static class elements:

    var _a;
class Foo {
  constructor() {
    __publicField(this, _a);
  }
  static {
    _a = b();
  }
  [a()]() {
  }
  static {
    c();
  }
}

    However, this could cause esbuild to accidentally generate a syntax error if the computed property key contains code that isn't allowed in a static block, such as an await expression. With this release, esbuild fixes this problem by shifting the computed property key backward to the previous spot in the evaluation order instead, which may push it into the extends clause or even before the class itself:

    // Original code
class Foo {
  [a()]() {}
  [await b()];
  static { c() }
}

// Old output (with --supported:class-field=false)
var _a;
class Foo {
  constructor() {
    __publicField(this, _a);
  }
  static {
    _a = await b();
  }
  [a()]() {
  }
  static {
    c();
  }
}

// New output (with --supported:class-field=false)
var _a, _b;
class Foo {
  constructor() {
    __publicField(this, _a);
  }
  [(_b = a(), _a = await b(), _b)]() {
  }
  static {
    c();
  }
}

  • Fix some --keep-names edge cases

    The NamedEvaluation syntax-directed operation in the JavaScript specification gives certain anonymous expressions a name property depending on where they are in the syntax tree. For example, the following initializers convey a name value:

    var foo = function() {}
var bar = class {}
console.log(foo.name, bar.name)

    When you enable esbuild's --keep-names setting, esbuild generates additional code to represent this NamedEvaluation operation so that the value of the name property persists even when the identifiers are renamed (e.g. due to minification).

    However, I recently learned that esbuild's implementation of NamedEvaluation is missing a few cases. Specifically esbuild was missing property definitions, class initializers, logical-assignment operators. These cases should now all be handled:

    var obj = { foo: function() {} }
class Foo0 { foo = function() {} }
class Foo1 { static foo = function() {} }
class Foo2 { accessor foo = function() {} }
class Foo3 { static accessor foo = function() {} }
foo ||= function() {}
foo &&= function() {}
foo ??= function() {}

v0.20.2

  • Support TypeScript experimental decorators on abstract class fields (#3684)

    With this release, you can now use TypeScript experimental decorators on abstract class fields. This was silently compiled incorrectly in esbuild 0.19.7 and below, and was an error from esbuild 0.19.8 to esbuild 0.20.1. Code such as the following should now work correctly:

    // Original code
const log = (x: any, y: string) => console.log(y)
abstract class Foo { @log abstract foo: string }
new class extends Foo { foo = '' }

// Old output (with --loader=ts --tsconfig-raw={\"compilerOptions\":{\"experimentalDecorators\":true}})
const log = (x, y) => console.log(y);
class Foo {
}
new class extends Foo {
  foo = "";
}();

// New output (with --loader=ts --tsconfig-raw={\"compilerOptions\":{\"experimentalDecorators\":true}})
const log = (x, y) => console.log(y);
class Foo {
}
__decorateClass([
  log
], Foo.prototype, "foo", 2);
new class extends Foo {
  foo = "";
}();

  • JSON loader now preserves __proto__ properties (#3700)

    Copying JSON source code into a JavaScript file will change its meaning if a JSON object contains the __proto__ key. A literal __proto__ property in a JavaScript object literal sets the prototype of the object instead of adding a property named __proto__, while a literal __proto__ property in a JSON object literal just adds a property named __proto__. With this release, esbuild will now work around this problem by converting JSON to JavaScript with a computed property key in this case:

    // Original code
import data from 'data:application/json,{"__proto__":{"fail":true}}'
if (Object.getPrototypeOf(data)?.fail) throw 'fail'

// Old output (with --bundle)
(() => {
  // <data:application/json,{"__proto__":{"fail":true}}>
  var json_proto_fail_true_default = { __proto__: { fail: true } };

  // entry.js
  if (Object.getPrototypeOf(json_proto_fail_true_default)?.fail)
    throw "fail";
})();

// New output (with --bundle)
(() => {
  // <data:application/json,{"__proto__":{"fail":true}}>
  var json_proto_fail_true_default = { ["__proto__"]: { fail: true } };

  // example.mjs
  if (Object.getPrototypeOf(json_proto_fail_true_default)?.fail)
    throw "fail";
})();

  • Improve dead code removal of switch statements (#3659)

    With this release, esbuild will now remove switch statements in branches when minifying if they are known to never be evaluated:

    // Original code
if (true) foo(); else switch (bar) { case 1: baz(); break }

// Old output (with --minify)
if(1)foo();else switch(bar){case 1:}

// New output (with --minify)
foo();

  • Empty enums should behave like an object literal (#3657)

    TypeScript allows you to create an empty enum and add properties to it at run time. While people usually use an empty object literal for this instead of a TypeScript enum, esbuild's enum transform didn't anticipate this use case and generated undefined instead of {} for an empty enum. With this release, you can now use an empty enum to generate an empty object literal.

    // Original code
enum Foo {}

// Old output (with --loader=ts)
var Foo = /* @__PURE__ */ ((Foo2) => {
})(Foo || {});

// New output (with --loader=ts)
var Foo = /* @__PURE__ */ ((Foo2) => {
  return Foo2;
})(Foo || {});

  • Handle Yarn Plug'n'Play edge case with tsconfig.json (#3698)

    Previously a tsconfig.json file that extends another file in a package with an exports map failed to work when Yarn's Plug'n'Play resolution was active. This edge case should work now starting with this release.

  • Work around issues with Deno 1.31+ (#3682)

    Version 0.20.0 of esbuild changed how the esbuild child process is run in esbuild's API for Deno. Previously it used Deno.run but that API is being removed in favor of Deno.Command. As part of this change, esbuild is now calling the new unref function on esbuild's long-lived child process, which is supposed to allow Deno to exit when your code has finished running even though the child process is still around (previously you had to explicitly call esbuild's stop() function to terminate the child process for Deno to be able to exit).

    However, this introduced a problem for Deno's testing API which now fails some tests that use esbuild with error: Promise resolution is still pending but the event loop has already resolved. It's unclear to me why this is happening. The call to unref was recommended by someone on the Deno core team, and calling Node's equivalent unref API has been working fine for esbuild in Node for a long time. It could be that I'm using it incorrectly, or that there's some reference counting and/or garbage collection bug in Deno's internals, or that Deno's unref just works differently than Node's unref. In any case, it's not good for Deno tests that use esbuild to be failing.

    In this release, I am removing the call to unref to fix this issue. This means that you will now have to call esbuild's stop() function to allow Deno to exit, just like you did before esbuild version 0.20.0 when this regression was introduced.

    Note: This regression wasn't caught earlier because Deno doesn't seem to fail tests that have outstanding setTimeout calls, which esbuild's test harness was using to enforce a maximum test runtime. Adding a setTimeout was allowing esbuild's Deno tests to succeed. So this regression doesn't necessarily apply to all people using tests in Deno.

✨ This PR was created by Minori, your friendly dependency updater! 🌸

## Dependency Update Updates **esbuild** from `0.19.12` to `0.27.2`. ### Type devDependencies ### Changelog ## Changelog ### v0.27.2 * Allow import path specifiers starting with `#/` ([#4361](https://github.com/evanw/esbuild/pull/4361)) Previously the specification for `package.json` disallowed import path specifiers starting with `#/`, but this restriction [has recently been relaxed](https://github.com/nodejs/node/pull/60864) and support for it is being added across the JavaScript ecosystem. One use case is using it for a wildcard pattern such as mapping `#/*` to `./src/*` (previously you had to use another character such as `#_*` instead, which was more confusing). There is some more context in [nodejs/node#49182](https://github.com/nodejs/node/issues/49182). This change was contributed by [@hybrist](https://github.com/hybrist). * Automatically add the `-webkit-mask` prefix ([#4357](https://github.com/evanw/esbuild/issues/4357), [#4358](https://github.com/evanw/esbuild/issues/4358)) This release automatically adds the `-webkit-` vendor prefix for the [`mask`](https://developer.mozilla.org/en-US/docs/Web/CSS/Reference/Properties/mask) CSS shorthand property: ```css /* Original code */ main { mask: url(x.png) center/5rem no-repeat } /* Old output (with --target=chrome110) */ main { mask: url(x.png) center/5rem no-repeat; } /* New output (with --target=chrome110) */ main { -webkit-mask: url(x.png) center/5rem no-repeat; mask: url(x.png) center/5rem no-repeat; } ``` This change was contributed by [@BPJEnnova](https://github.com/BPJEnnova). * Additional minification of `switch` statements ([#4176](https://github.com/evanw/esbuild/issues/4176), [#4359](https://github.com/evanw/esbuild/issues/4359)) This release contains additional minification patterns for reducing `switch` statements. Here is an example: ```js // Original code switch (x) { case 0: foo() break case 1: default: bar() } // Old output (with --minify) switch(x){case 0:foo();break;case 1:default:bar()} // New output (with --minify) x===0?foo():bar(); ``` * Forbid `using` declarations inside `switch` clauses ([#4323](https://github.com/evanw/esbuild/issues/4323)) This is a rare change to remove something that was previously possible. The [Explicit Resource Management](https://github.com/tc39/proposal-explicit-resource-management) proposal introduced `using` declarations. These were previously allowed inside `case` and `default` clauses in `switch` statements. This had well-defined semantics and was already widely implemented (by V8, SpiderMonkey, TypeScript, esbuild, and others). However, it was considered to be too confusing because of how scope works in switch statements, so it has been removed from the specification. This edge case will now be a syntax error. See [tc39/proposal-explicit-resource-management#215](https://github.com/tc39/proposal-explicit-resource-management/issues/215) and [rbuckton/ecma262#14](https://github.com/rbuckton/ecma262/pull/14) for details. Here is an example of code that is no longer allowed: ```js switch (mode) { case 'read': using readLock = db.read() return readAll(readLock) case 'write': using writeLock = db.write() return writeAll(writeLock) } ``` That code will now have to be modified to look like this instead (note the additional `{` and `}` block statements around each case body): ```js switch (mode) { case 'read': { using readLock = db.read() return readAll(readLock) } case 'write': { using writeLock = db.write() return writeAll(writeLock) } } ``` This is not being released in one of esbuild's breaking change releases since this feature hasn't been finalized yet, and esbuild always tracks the current state of the specification (so esbuild's previous behavior was arguably incorrect). ### v0.27.1 * Fix bundler bug with `var` nested inside `if` ([#4348](https://github.com/evanw/esbuild/issues/4348)) This release fixes a bug with the bundler that happens when importing an ES module using `require` (which causes it to be wrapped) and there's a top-level `var` inside an `if` statement without being wrapped in a `{ ... }` block (and a few other conditions). The bundling transform needed to hoist these `var` declarations outside of the lazy ES module wrapper for correctness. See the issue for details. * Fix minifier bug with `for` inside `try` inside label ([#4351](https://github.com/evanw/esbuild/issues/4351)) This fixes an old regression from [version v0.21.4](https://github.com/evanw/esbuild/releases/v0.21.4). Some code was introduced to move the label inside the `try` statement to address a problem with transforming labeled `for await` loops to avoid the `await` (the transformation involves converting the `for await` loop into a `for` loop and wrapping it in a `try` statement). However, it introduces problems for cross-compiled JVM code that uses all three of these features heavily. This release restricts this transform to only apply to `for` loops that esbuild itself generates internally as part of the `for await` transform. Here is an example of some affected code: ```js // Original code d: { e: { try { while (1) { break d } } catch { break e; } } } // Old output (with --minify) a:try{e:for(;;)break a}catch{break e} // New output (with --minify) a:e:try{for(;;)break a}catch{break e} ``` * Inline IIFEs containing a single expression ([#4354](https://github.com/evanw/esbuild/issues/4354)) Previously inlining of IIFEs (immediately-invoked function expressions) only worked if the body contained a single `return` statement. Now it should also work if the body contains a single expression statement instead: ```js // Original code const foo = () => { const cb = () => { console.log(x()) } return cb() } // Old output (with --minify) const foo=()=>(()=>{console.log(x())})(); // New output (with --minify) const foo=()=>{console.log(x())}; ``` * The minifier now strips empty `finally` clauses ([#4353](https://github.com/evanw/esbuild/issues/4353)) This improvement means that `finally` clauses containing dead code can potentially cause the associated `try` statement to be removed from the output entirely in minified builds: ```js // Original code function foo(callback) { if (DEBUG) stack.push(callback.name); try { callback(); } finally { if (DEBUG) stack.pop(); } } // Old output (with --minify --define:DEBUG=false) function foo(a){try{a()}finally{}} // New output (with --minify --define:DEBUG=false) function foo(a){a()} ``` * Allow tree-shaking of the `Symbol` constructor With this release, calling `Symbol` is now considered to be side-effect free when the argument is known to be a primitive value. This means esbuild can now tree-shake module-level symbol variables: ```js // Original code const a = Symbol('foo') const b = Symbol(bar) // Old output (with --tree-shaking=true) const a = Symbol("foo"); const b = Symbol(bar); // New output (with --tree-shaking=true) const b = Symbol(bar); ``` ### v0.27.0 **This release deliberately contains backwards-incompatible changes.** To avoid automatically picking up releases like this, you should either be pinning the exact version of `esbuild` in your `package.json` file (recommended) or be using a version range syntax that only accepts patch upgrades such as `^0.26.0` or `~0.26.0`. See npm's documentation about [semver](https://docs.npmjs.com/cli/v6/using-npm/semver/) for more information. * Use `Uint8Array.fromBase64` if available ([#4286](https://github.com/evanw/esbuild/issues/4286)) With this release, esbuild's `binary` loader will now use the new [`Uint8Array.fromBase64`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Uint8Array/fromBase64) function unless it's unavailable in the configured target environment. If it's unavailable, esbuild's previous code for this will be used as a fallback. Note that this means you may now need to specify `target` when using this feature with Node (for example `--target=node22`) unless you're using Node v25+. * Update the Go compiler from v1.23.12 to v1.25.4 ([#4208](https://github.com/evanw/esbuild/issues/4208), [#4311](https://github.com/evanw/esbuild/pull/4311)) This raises the operating system requirements for running esbuild: * Linux: now requires a kernel version of 3.2 or later * macOS: now requires macOS 12 (Monterey) or later ### v0.26.0 * Enable trusted publishing ([#4281](https://github.com/evanw/esbuild/issues/4281)) GitHub and npm are recommending that maintainers for packages such as esbuild switch to [trusted publishing](https://docs.npmjs.com/trusted-publishers). With this release, a VM on GitHub will now build and publish all of esbuild's packages to npm instead of me. In theory. Unfortunately there isn't really a way to test that this works other than to do it live. So this release is that live test. Hopefully this release is uneventful and is exactly the same as the previous one (well, except for the green provenance attestation checkmark on npm that happens with trusted publishing). ### v0.25.12 * Fix a minification regression with CSS media queries ([#4315](https://github.com/evanw/esbuild/issues/4315)) The previous release introduced support for parsing media queries which unintentionally introduced a regression with the removal of duplicate media rules during minification. Specifically the grammar for `@media <media-type> and <media-condition-without-or> { ... }` was missing an equality check for the `<media-condition-without-or>` part, so rules with different suffix clauses in this position would incorrectly compare equal and be deduplicated. This release fixes the regression. * Update the list of known JavaScript globals ([#4310](https://github.com/evanw/esbuild/issues/4310)) This release updates esbuild's internal list of known JavaScript globals. These are globals that are known to not have side-effects when the property is accessed. For example, accessing the global `Array` property is considered to be side-effect free but accessing the global `scrollY` property can trigger a layout, which is a side-effect. This is used by esbuild's tree-shaking to safely remove unused code that is known to be side-effect free. This update adds the following global properties: From [ES2017](https://tc39.es/ecma262/2017/): - `Atomics` - `SharedArrayBuffer` From [ES2020](https://tc39.es/ecma262/2020/): - `BigInt64Array` - `BigUint64Array` From [ES2021](https://tc39.es/ecma262/2021/): - `FinalizationRegistry` - `WeakRef` From [ES2025](https://tc39.es/ecma262/2025/): - `Float16Array` - `Iterator` Note that this does not indicate that constructing any of these objects is side-effect free, just that accessing the identifier is side-effect free. For example, this now allows esbuild to tree-shake classes that extend from `Iterator`: ```js // This can now be tree-shaken by esbuild: class ExampleIterator extends Iterator {} ``` * Add support for the new `@view-transition` CSS rule ([#4313](https://github.com/evanw/esbuild/pull/4313)) With this release, esbuild now has improved support for pretty-printing and minifying the new `@view-transition` rule (which esbuild was previously unaware of): ```css /* Original code */ @view-transition { navigation: auto; types: check; } /* Old output */ @view-transition { navigation: auto; types: check; } /* New output */ @view-transition { navigation: auto; types: check; } ``` The new view transition feature provides a mechanism for creating animated transitions between documents in a multi-page app. You can read more about view transition rules [here](https://developer.mozilla.org/en-US/docs/Web/CSS/@view-transition). This change was contributed by [@yisibl](https://github.com/yisibl). * Trim CSS rules that will never match The CSS minifier will now remove rules whose selectors contain `:is()` and `:where()` as those selectors will never match. These selectors can currently be automatically generated by esbuild when you give esbuild nonsensical input such as the following: ```css /* Original code */ div:before { color: green; &.foo { color: red; } } /* Old output (with --supported:nesting=false --minify) */ div:before{color:green}:is().foo{color:red} /* New output (with --supported:nesting=false --minify) */ div:before{color:green} ``` This input is nonsensical because CSS nesting is (unfortunately) not supported inside of pseudo-elements such as `:before`. Currently esbuild generates a rule containing `:is()` in this case when you tell esbuild to transform nested CSS into non-nested CSS. I think it's reasonable to do that as it sort of helps explain what's going on (or at least indicates that something is wrong in the output). It shouldn't be present in minified code, however, so this release now strips it out. ### v0.25.11 * Add support for `with { type: 'bytes' }` imports ([#4292](https://github.com/evanw/esbuild/issues/4292)) The [import bytes](https://github.com/tc39/proposal-import-bytes) proposal has reached stage 2.7 in the TC39 process, which means that although it isn't quite recommended for implementation, it's generally approved and ready for validation. Furthermore it has already been implemented by [Deno](https://docs.deno.com/examples/importing_bytes/) and [Webpack](https://github.com/webpack/webpack/pull/19928). So with this release, esbuild will also add support for this. It behaves exactly the same as esbuild's existing [`binary` loader](https://esbuild.github.io/content-types/#binary). Here's an example: ```js import data from './image.png' with { type: 'bytes' } const view = new DataView(data.buffer, 0, 24) const width = view.getInt32(16) const height = view.getInt32(20) console.log('size:', width + '\xD7' + height) ``` * Lower CSS media query range syntax ([#3748](https://github.com/evanw/esbuild/issues/3748), [#4293](https://github.com/evanw/esbuild/issues/4293)) With this release, esbuild will now transform CSS media query range syntax into equivalent syntax using `min-`/`max-` prefixes for older browsers. For example, the following CSS: ```css @media (640px <= width <= 960px) { main { display: flex; } } ``` will be transformed like this with a target such as `--target=chrome100` (or more specifically with `--supported:media-range=false` if desired): ```css @media (min-width: 640px) and (max-width: 960px) { main { display: flex; } } ``` ### v0.25.10 * Fix a panic in a minification edge case ([#4287](https://github.com/evanw/esbuild/issues/4287)) This release fixes a panic due to a null pointer that could happen when esbuild inlines a doubly-nested identity function and the final result is empty. It was fixed by emitting the value `undefined` in this case, which avoids the panic. This case must be rare since it hasn't come up until now. Here is an example of code that previously triggered the panic (which only happened when minifying): ```js function identity(x) { return x } identity({ y: identity(123) }) ``` * Fix `@supports` nested inside pseudo-element ([#4265](https://github.com/evanw/esbuild/issues/4265)) When transforming nested CSS to non-nested CSS, esbuild is supposed to filter out pseudo-elements such as `::placeholder` for correctness. The [CSS nesting specification](https://www.w3.org/TR/css-nesting-1/) says the following: > The nesting selector cannot represent pseudo-elements (identical to the behavior of the ':is()' pseudo-class). We’d like to relax this restriction, but need to do so simultaneously for both ':is()' and '&', since they’re intentionally built on the same underlying mechanisms. However, it seems like this behavior is different for nested at-rules such as `@supports`, which do work with pseudo-elements. So this release modifies esbuild's behavior to now take that into account: ```css /* Original code */ ::placeholder { color: red; body & { color: green } @supports (color: blue) { color: blue } } /* Old output (with --supported:nesting=false) */ ::placeholder { color: red; } body :is() { color: green; } @supports (color: blue) { { color: blue; } } /* New output (with --supported:nesting=false) */ ::placeholder { color: red; } body :is() { color: green; } @supports (color: blue) { ::placeholder { color: blue; } } ``` ### v0.25.9 * Better support building projects that use Yarn on Windows ([#3131](https://github.com/evanw/esbuild/issues/3131), [#3663](https://github.com/evanw/esbuild/issues/3663)) With this release, you can now use esbuild to bundle projects that use Yarn Plug'n'Play on Windows on drives other than the `C:` drive. The problem was as follows: 1. Yarn in Plug'n'Play mode on Windows stores its global module cache on the `C:` drive 2. Some developers put their projects on the `D:` drive 3. Yarn generates relative paths that use `../..` to get from the project directory to the cache directory 4. Windows-style paths don't support directory traversal between drives via `..` (so `D:\..` is just `D:`) 5. I didn't have access to a Windows machine for testing this edge case Yarn works around this edge case by pretending Windows-style paths beginning with `C:\` are actually Unix-style paths beginning with `/C:/`, so the `../..` path segments are able to navigate across drives inside Yarn's implementation. This was broken for a long time in esbuild but I finally got access to a Windows machine and was able to debug and fix this edge case. So you should now be able to bundle these projects with esbuild. * Preserve parentheses around function expressions ([#4252](https://github.com/evanw/esbuild/issues/4252)) The V8 JavaScript VM uses parentheses around function expressions as an optimization hint to immediately compile the function. Otherwise the function would be lazily-compiled, which has additional overhead if that function is always called immediately as lazy compilation involves parsing the function twice. You can read [V8's blog post about this](https://v8.dev/blog/preparser) for more details. Previously esbuild did not represent parentheses around functions in the AST so they were lost during compilation. With this change, esbuild will now preserve parentheses around function expressions when they are present in the original source code. This means these optimization hints will not be lost when bundling with esbuild. In addition, esbuild will now automatically add this optimization hint to immediately-invoked function expressions. Here's an example: ```js // Original code const fn0 = () => 0 const fn1 = (() => 1) console.log(fn0, function() { return fn1() }()) // Old output const fn0 = () => 0; const fn1 = () => 1; console.log(fn0, function() { return fn1(); }()); // New output const fn0 = () => 0; const fn1 = (() => 1); console.log(fn0, (function() { return fn1(); })()); ``` Note that you do not want to wrap all function expressions in parentheses. This optimization hint should only be used for functions that are called on initial load. Using this hint for functions that are not called on initial load will unnecessarily delay the initial load. Again, see V8's blog post linked above for details. * Update Go from 1.23.10 to 1.23.12 ([#4257](https://github.com/evanw/esbuild/issues/4257), [#4258](https://github.com/evanw/esbuild/pull/4258)) This should have no effect on existing code as this version change does not change Go's operating system support. It may remove certain false positive reports (specifically CVE-2025-4674 and CVE-2025-47907) from vulnerability scanners that only detect which version of the Go compiler esbuild uses. ### v0.25.8 * Fix another TypeScript parsing edge case ([#4248](https://github.com/evanw/esbuild/issues/4248)) This fixes a regression with a change in the previous release that tries to more accurately parse TypeScript arrow functions inside the `?:` operator. The regression specifically involves parsing an arrow function containing a `#private` identifier inside the middle of a `?:` ternary operator inside a class body. This was fixed by propagating private identifier state into the parser clone used to speculatively parse the arrow function body. Here is an example of some affected code: ```ts class CachedDict { #has = (a: string) => dict.has(a); has = window ? (word: string): boolean => this.#has(word) : this.#has; } ``` * Fix a regression with the parsing of source phase imports The change in the previous release to parse [source phase imports](https://github.com/tc39/proposal-source-phase-imports) failed to properly handle the following cases: ```ts import source from 'bar' import source from from 'bar' import source type foo from 'bar' ``` Parsing for these cases should now be fixed. The first case was incorrectly treated as a syntax error because esbuild was expecting the second case. And the last case was previously allowed but is now forbidden. TypeScript hasn't added this feature yet so it remains to be seen whether the last case will be allowed, but it's safer to disallow it for now. At least Babel doesn't allow the last case when parsing TypeScript, and Babel was involved with the source phase import specification. ### v0.25.7 * Parse and print JavaScript imports with an explicit phase ([#4238](https://github.com/evanw/esbuild/issues/4238)) This release adds basic syntax support for the `defer` and `source` import phases in JavaScript: * `defer` This is a [stage 3 proposal](https://github.com/tc39/proposal-defer-import-eval) for an upcoming JavaScript feature that will provide one way to eagerly load but lazily initialize imported modules. The imported module is automatically initialized on first use. Support for this syntax will also be part of the upcoming release of [TypeScript 5.9](https://devblogs.microsoft.com/typescript/announcing-typescript-5-9-beta/#support-for-import-defer). The syntax looks like this: ```js import defer * as foo from "<specifier>"; const bar = await import.defer("<specifier>"); ``` Note that this feature deliberately cannot be used with the syntax `import defer foo from "<specifier>"` or `import defer { foo } from "<specifier>"`. * `source` This is a [stage 3 proposal](https://github.com/tc39/proposal-source-phase-imports) for an upcoming JavaScript feature that will provide another way to eagerly load but lazily initialize imported modules. The imported module is returned in an uninitialized state. Support for this syntax may or may not be a part of TypeScript 5.9 (see [this issue](https://github.com/microsoft/TypeScript/issues/61216) for details). The syntax looks like this: ```js import source foo from "<specifier>"; const bar = await import.source("<specifier>"); ``` Note that this feature deliberately cannot be used with the syntax `import defer * as foo from "<specifier>"` or `import defer { foo } from "<specifier>"`. This change only adds support for this syntax. These imports cannot currently be bundled by esbuild. To use these new features with esbuild's bundler, the imported paths must be external to the bundle and the output format must be set to `esm`. * Support optionally emitting absolute paths instead of relative paths ([#338](https://github.com/evanw/esbuild/issues/338), [#2082](https://github.com/evanw/esbuild/issues/2082), [#3023](https://github.com/evanw/esbuild/issues/3023)) This release introduces the `--abs-paths=` feature which takes a comma-separated list of situations where esbuild should use absolute paths instead of relative paths. There are currently three supported situations: `code` (comments and string literals), `log` (log message text and location info), and `metafile` (the JSON build metadata). Using absolute paths instead of relative paths is not the default behavior because it means that the build results are no longer machine-independent (which means builds are no longer reproducible). Absolute paths can be useful when used with certain terminal emulators that allow you to click on absolute paths in the terminal text and/or when esbuild is being automatically invoked from several different directories within the same script. * Fix a TypeScript parsing edge case ([#4241](https://github.com/evanw/esbuild/issues/4241)) This release fixes an edge case with parsing an arrow function in TypeScript with a return type that's in the middle of a `?:` ternary operator. For example: ```ts x = a ? (b) : c => d; y = a ? (b) : c => d : e; ``` The `:` token in the value assigned to `x` pairs with the `?` token, so it's not the start of a return type annotation. However, the first `:` token in the value assigned to `y` is the start of a return type annotation because after parsing the arrow function body, it turns out there's another `:` token that can be used to pair with the `?` token. This case is notable as it's the first TypeScript edge case that esbuild has needed a backtracking parser to parse. It has been addressed by a quick hack (cloning the whole parser) as it's a rare edge case and esbuild doesn't otherwise need a backtracking parser. Hopefully this is sufficient and doesn't cause any issues. * Inline small constant strings when minifying Previously esbuild's minifier didn't inline string constants because strings can be arbitrarily long, and this isn't necessarily a size win if the string is used more than once. Starting with this release, esbuild will now inline string constants when the length of the string is three code units or less. For example: ```js // Original code const foo = 'foo' console.log({ [foo]: true }) // Old output (with --minify --bundle --format=esm) var o="foo";console.log({[o]:!0}); // New output (with --minify --bundle --format=esm) console.log({foo:!0}); ``` Note that esbuild's constant inlining only happens in very restrictive scenarios to avoid issues with TDZ handling. This change doesn't change when esbuild's constant inlining happens. It only expands the scope of it to include certain string literals in addition to numeric and boolean literals. ### v0.25.6 * Fix a memory leak when `cancel()` is used on a build context ([#4231](https://github.com/evanw/esbuild/issues/4231)) Calling `rebuild()` followed by `cancel()` in rapid succession could previously leak memory. The bundler uses a producer/consumer model internally, and the resource leak was caused by the consumer being termianted while there were still remaining unreceived results from a producer. To avoid the leak, the consumer now waits for all producers to finish before terminating. * Support empty `:is()` and `:where()` syntax in CSS ([#4232](https://github.com/evanw/esbuild/issues/4232)) Previously using these selectors with esbuild would generate a warning. That warning has been removed in this release for these cases. * Improve tree-shaking of `try` statements in dead code ([#4224](https://github.com/evanw/esbuild/issues/4224)) With this release, esbuild will now remove certain `try` statements if esbuild considers them to be within dead code (i.e. code that is known to not ever be evaluated). For example: ```js // Original code return 'foo' try { return 'bar' } catch {} // Old output (with --minify) return"foo";try{return"bar"}catch{} // New output (with --minify) return"foo"; ``` * Consider negated bigints to have no side effects While esbuild currently considers `1`, `-1`, and `1n` to all have no side effects, it didn't previously consider `-1n` to have no side effects. This is because esbuild does constant folding with numbers but not bigints. However, it meant that unused negative bigint constants were not tree-shaken. With this release, esbuild will now consider these expressions to also be side-effect free: ```js // Original code let a = 1, b = -1, c = 1n, d = -1n // Old output (with --bundle --minify) (()=>{var n=-1n;})(); // New output (with --bundle --minify) (()=>{})(); ``` * Support a configurable delay in watch mode before rebuilding ([#3476](https://github.com/evanw/esbuild/issues/3476), [#4178](https://github.com/evanw/esbuild/issues/4178)) The `watch()` API now takes a `delay` option that lets you add a delay (in milliseconds) before rebuilding when a change is detected in watch mode. If you use a tool that regenerates multiple source files very slowly, this should make it more likely that esbuild's watch mode won't generate a broken intermediate build before the successful final build. This option is also available via the CLI using the `--watch-delay=` flag. This should also help avoid confusion about the `watch()` API's options argument. It was previously empty to allow for future API expansion, which caused some people to think that the documentation was missing. It's no longer empty now that the `watch()` API has an option. * Allow mixed array for `entryPoints` API option ([#4223](https://github.com/evanw/esbuild/issues/4223)) The TypeScript type definitions now allow you to pass a mixed array of both string literals and object literals to the `entryPoints` API option, such as `['foo.js', { out: 'lib', in: 'bar.js' }]`. This was always possible to do in JavaScript but the TypeScript type definitions were previously too restrictive. * Update Go from 1.23.8 to 1.23.10 ([#4204](https://github.com/evanw/esbuild/issues/4204), [#4207](https://github.com/evanw/esbuild/pull/4207)) This should have no effect on existing code as this version change does not change Go's operating system support. It may remove certain false positive reports (specifically CVE-2025-4673 and CVE-2025-22874) from vulnerability scanners that only detect which version of the Go compiler esbuild uses. * Experimental support for esbuild on OpenHarmony ([#4212](https://github.com/evanw/esbuild/pull/4212)) With this release, esbuild now publishes the [`@esbuild/openharmony-arm64`](https://www.npmjs.com/package/@esbuild/openharmony-arm64) npm package for [OpenHarmony](https://en.wikipedia.org/wiki/OpenHarmony). It contains a WebAssembly binary instead of a native binary because Go doesn't currently support OpenHarmony. Node does support it, however, so in theory esbuild should now work on OpenHarmony through WebAssembly. This change was contributed by [@hqzing](https://github.com/hqzing). ### v0.25.5 * Fix a regression with `browser` in `package.json` ([#4187](https://github.com/evanw/esbuild/issues/4187)) The fix to [#4144](https://github.com/evanw/esbuild/issues/4144) in version 0.25.3 introduced a regression that caused `browser` overrides specified in `package.json` to fail to override relative path names that end in a trailing slash. That behavior change affected the `axios@0.30.0` package. This regression has been fixed, and now has test coverage. * Add support for certain keywords as TypeScript tuple labels ([#4192](https://github.com/evanw/esbuild/issues/4192)) Previously esbuild could incorrectly fail to parse certain keywords as TypeScript tuple labels that are parsed by the official TypeScript compiler if they were followed by a `?` modifier. These labels included `function`, `import`, `infer`, `new`, `readonly`, and `typeof`. With this release, these keywords will now be parsed correctly. Here's an example of some affected code: ```ts type Foo = [ value: any, readonly?: boolean, // This is now parsed correctly ] ``` * Add CSS prefixes for the `stretch` sizing value ([#4184](https://github.com/evanw/esbuild/issues/4184)) This release adds support for prefixing CSS declarations such as `div { width: stretch }`. That CSS is now transformed into this depending on what the `--target=` setting includes: ```css div { width: -webkit-fill-available; width: -moz-available; width: stretch; } ``` ### v0.25.4 * Add simple support for CORS to esbuild's development server ([#4125](https://github.com/evanw/esbuild/issues/4125)) Starting with version 0.25.0, esbuild's development server is no longer configured to serve cross-origin requests. This was a deliberate change to prevent any website you visit from accessing your running esbuild development server. However, this change prevented (by design) certain use cases such as "debugging in production" by having your production website load code from `localhost` where the esbuild development server is running. To enable this use case, esbuild is adding a feature to allow [Cross-Origin Resource Sharing](https://developer.mozilla.org/en-US/docs/Web/HTTP/Guides/CORS) (a.k.a. CORS) for [simple requests](https://developer.mozilla.org/en-US/docs/Web/HTTP/Guides/CORS#simple_requests). Specifically, passing your origin to the new `cors` option will now set the `Access-Control-Allow-Origin` response header when the request has a matching `Origin` header. Note that this currently only works for requests that don't send a preflight `OPTIONS` request, as esbuild's development server doesn't currently support `OPTIONS` requests. Some examples: * **CLI:** ``` esbuild --servedir=. --cors-origin=https://example.com ``` * **JS:** ```js const ctx = await esbuild.context({}) await ctx.serve({ servedir: '.', cors: { origin: 'https://example.com', }, }) ``` * **Go:** ```go ctx, _ := api.Context(api.BuildOptions{}) ctx.Serve(api.ServeOptions{ Servedir: ".", CORS: api.CORSOptions{ Origin: []string{"https://example.com"}, }, }) ``` The special origin `*` can be used to allow any origin to access esbuild's development server. Note that this means any website you visit will be able to read everything served by esbuild. * Pass through invalid URLs in source maps unmodified ([#4169](https://github.com/evanw/esbuild/issues/4169)) This fixes a regression in version 0.25.0 where `sources` in source maps that form invalid URLs were not being passed through to the output. Version 0.25.0 changed the interpretation of `sources` from file paths to URLs, which means that URL parsing can now fail. Previously URLs that couldn't be parsed were replaced with the empty string. With this release, invalid URLs in `sources` should now be passed through unmodified. * Handle exports named `__proto__` in ES modules ([#4162](https://github.com/evanw/esbuild/issues/4162), [#4163](https://github.com/evanw/esbuild/pull/4163)) In JavaScript, the special property name `__proto__` sets the prototype when used inside an object literal. Previously esbuild's ESM-to-CommonJS conversion didn't special-case the property name of exports named `__proto__` so the exported getter accidentally became the prototype of the object literal. It's unclear what this affects, if anything, but it's better practice to avoid this by using a computed property name in this case. This fix was contributed by [@magic-akari](https://github.com/magic-akari). ### v0.25.3 * Fix lowered `async` arrow functions before `super()` ([#4141](https://github.com/evanw/esbuild/issues/4141), [#4142](https://github.com/evanw/esbuild/pull/4142)) This change makes it possible to call an `async` arrow function in a constructor before calling `super()` when targeting environments without `async` support, as long as the function body doesn't reference `this`. Here's an example (notice the change from `this` to `null`): ```js // Original code class Foo extends Object { constructor() { (async () => await foo())() super() } } // Old output (with --target=es2016) class Foo extends Object { constructor() { (() => __async(this, null, function* () { return yield foo(); }))(); super(); } } // New output (with --target=es2016) class Foo extends Object { constructor() { (() => __async(null, null, function* () { return yield foo(); }))(); super(); } } ``` Some background: Arrow functions with the `async` keyword are transformed into generator functions for older language targets such as `--target=es2016`. Since arrow functions capture `this`, the generated code forwards `this` into the body of the generator function. However, JavaScript class syntax forbids using `this` in a constructor before calling `super()`, and this forwarding was problematic since previously happened even when the function body doesn't use `this`. Starting with this release, esbuild will now only forward `this` if it's used within the function body. This fix was contributed by [@magic-akari](https://github.com/magic-akari). * Fix memory leak with `--watch=true` ([#4131](https://github.com/evanw/esbuild/issues/4131), [#4132](https://github.com/evanw/esbuild/pull/4132)) This release fixes a memory leak with esbuild when `--watch=true` is used instead of `--watch`. Previously using `--watch=true` caused esbuild to continue to use more and more memory for every rebuild, but `--watch=true` should now behave like `--watch` and not leak memory. This bug happened because esbuild disables the garbage collector when it's not run as a long-lived process for extra speed, but esbuild's checks for which arguments cause esbuild to be a long-lived process weren't updated for the new `--watch=true` style of boolean command-line flags. This has been an issue since this boolean flag syntax was added in version 0.14.24 in 2022. These checks are unfortunately separate from the regular argument parser because of how esbuild's internals are organized (the command-line interface is exposed as a separate [Go API](https://pkg.go.dev/github.com/evanw/esbuild/pkg/cli) so you can build your own custom esbuild CLI). This fix was contributed by [@mxschmitt](https://github.com/mxschmitt). * More concise output for repeated legal comments ([#4139](https://github.com/evanw/esbuild/issues/4139)) Some libraries have many files and also use the same legal comment text in all files. Previously esbuild would copy each legal comment to the output file. Starting with this release, legal comments duplicated across separate files will now be grouped in the output file by unique comment content. * Allow a custom host with the development server ([#4110](https://github.com/evanw/esbuild/issues/4110)) With this release, you can now use a custom non-IP `host` with esbuild's local development server (either with `--serve=` for the CLI or with the `serve()` call for the API). This was previously possible, but was intentionally broken in [version 0.25.0](https://github.com/evanw/esbuild/releases/v0.25.0) to fix a security issue. This change adds the functionality back except that it's now opt-in and only for a single domain name that you provide. For example, if you add a mapping in your `/etc/hosts` file from `local.example.com` to `127.0.0.1` and then use `esbuild --serve=local.example.com:8000`, you will now be able to visit http://local.example.com:8000/ in your browser and successfully connect to esbuild's development server (doing that would previously have been blocked by the browser). This should also work with HTTPS if it's enabled (see esbuild's documentation for how to do that). * Add a limit to CSS nesting expansion ([#4114](https://github.com/evanw/esbuild/issues/4114)) With this release, esbuild will now fail with an error if there is too much CSS nesting expansion. This can happen when nested CSS is converted to CSS without nesting for older browsers as expanding CSS nesting is inherently exponential due to the resulting combinatorial explosion. The expansion limit is currently hard-coded and cannot be changed, but is extremely unlikely to trigger for real code. It exists to prevent esbuild from using too much time and/or memory. Here's an example: ```css a,b{a,b{a,b{a,b{a,b{a,b{a,b{a,b{a,b{a,b{a,b{a,b{a,b{a,b{a,b{a,b{a,b{a,b{a,b{a,b{color:red}}}}}}}}}}}}}}}}}}}} ``` Previously, transforming this file with `--target=safari1` took 5 seconds and generated 40mb of CSS. Trying to do that will now generate the following error instead: ``` ✘ [ERROR] CSS nesting is causing too much expansion example.css:1:60: 1 │ a,b{a,b{a,b{a,b{a,b{a,b{a,b{a,b{a,b{a,b{a,b{a,b{a,b{a,b{a,b{a,b{a,b{a,b{a,b{a,b{color:red}}}}}}}}}}}}}}}}}}}} ╵ ^ CSS nesting expansion was terminated because a rule was generated with 65536 selectors. This limit exists to prevent esbuild from using too much time and/or memory. Please change your CSS to use fewer levels of nesting. ``` * Fix path resolution edge case ([#4144](https://github.com/evanw/esbuild/issues/4144)) This fixes an edge case where esbuild's path resolution algorithm could deviate from node's path resolution algorithm. It involves a confusing situation where a directory shares the same file name as a file (but without the file extension). See the linked issue for specific details. This appears to be a case where esbuild is correctly following [node's published resolution algorithm](https://nodejs.org/api/modules.html#all-together) but where node itself is doing something different. Specifically the step `LOAD_AS_FILE` appears to be skipped when the input ends with `..`. This release changes esbuild's behavior for this edge case to match node's behavior. * Update Go from 1.23.7 to 1.23.8 ([#4133](https://github.com/evanw/esbuild/issues/4133), [#4134](https://github.com/evanw/esbuild/pull/4134)) This should have no effect on existing code as this version change does not change Go's operating system support. It may remove certain reports from vulnerability scanners that detect which version of the Go compiler esbuild uses, such as for CVE-2025-22871. As a reminder, esbuild's development server is intended for development, not for production, so I do not consider most networking-related vulnerabilities in Go to be vulnerabilities in esbuild. Please do not use esbuild's development server in production. ### v0.25.2 * Support flags in regular expressions for the API ([#4121](https://github.com/evanw/esbuild/issues/4121)) The JavaScript plugin API for esbuild takes JavaScript regular expression objects for the `filter` option. Internally these are translated into Go regular expressions. However, this translation previously ignored the `flags` property of the regular expression. With this release, esbuild will now translate JavaScript regular expression flags into Go regular expression flags. Specifically the JavaScript regular expression `/\.[jt]sx?$/i` is turned into the Go regular expression `` `(?i)\.[jt]sx?$` `` internally inside of esbuild's API. This should make it possible to use JavaScript regular expressions with the `i` flag. Note that JavaScript and Go don't support all of the same regular expression features, so this mapping is only approximate. * Fix node-specific annotations for string literal export names ([#4100](https://github.com/evanw/esbuild/issues/4100)) When node instantiates a CommonJS module, it scans the AST to look for names to expose via ESM named exports. This is a heuristic that looks for certain patterns such as `exports.NAME = ...` or `module.exports = { ... }`. This behavior is used by esbuild to "annotate" CommonJS code that was converted from ESM with the original ESM export names. For example, when converting the file `export let foo, bar` from ESM to CommonJS, esbuild appends this to the end of the file: ```js // Annotate the CommonJS export names for ESM import in node: 0 && (module.exports = { bar, foo }); ``` However, this feature previously didn't work correctly for export names that are not valid identifiers, which can be constructed using string literal export names. The generated code contained a syntax error. That problem is fixed in this release: ```js // Original code let foo export { foo as "foo!" } // Old output (with --format=cjs --platform=node) ... 0 && (module.exports = { "foo!" }); // New output (with --format=cjs --platform=node) ... 0 && (module.exports = { "foo!": null }); ``` * Basic support for index source maps ([#3439](https://github.com/evanw/esbuild/issues/3439), [#4109](https://github.com/evanw/esbuild/pull/4109)) The source map specification has an optional mode called [index source maps](https://tc39.es/ecma426/#sec-index-source-map) that makes it easier for tools to create an aggregate JavaScript file by concatenating many smaller JavaScript files with source maps, and then generate an aggregate source map by simply providing the original source maps along with some offset information. My understanding is that this is rarely used in practice. I'm only aware of two uses of it in the wild: [ClojureScript](https://clojurescript.org/) and [Turbopack](https://turbo.build/pack/). This release provides basic support for indexed source maps. However, the implementation has not been tested on a real app (just on very simple test input). If you are using index source maps in a real app, please try this out and report back if anything isn't working for you. Note that this is also not a complete implementation. For example, index source maps technically allows nesting source maps to an arbitrary depth, while esbuild's implementation in this release only supports a single level of nesting. It's unclear whether supporting more than one level of nesting is important or not given the lack of available test cases. This feature was contributed by [@clyfish](https://github.com/clyfish). ### v0.25.1 * Fix incorrect paths in inline source maps ([#4070](https://github.com/evanw/esbuild/issues/4070), [#4075](https://github.com/evanw/esbuild/issues/4075), [#4105](https://github.com/evanw/esbuild/issues/4105)) This fixes a regression from version 0.25.0 where esbuild didn't correctly resolve relative paths contained within source maps in inline `sourceMappingURL` data URLs. The paths were incorrectly being passed through as-is instead of being resolved relative to the source file containing the `sourceMappingURL` comment, which was due to the data URL not being a file URL. This regression has been fixed, and this case now has test coverage. * Fix invalid generated source maps ([#4080](https://github.com/evanw/esbuild/issues/4080), [#4082](https://github.com/evanw/esbuild/issues/4082), [#4104](https://github.com/evanw/esbuild/issues/4104), [#4107](https://github.com/evanw/esbuild/issues/4107)) This release fixes a regression from version 0.24.1 that could cause esbuild to generate invalid source maps. Specifically under certain conditions, esbuild could generate a mapping with an out-of-bounds source index. It was introduced by code that attempted to improve esbuild's handling of "null" entries in source maps (i.e. mappings with a generated position but no original position). This regression has been fixed. This fix was contributed by [@jridgewell](https://github.com/jridgewell). * Fix a regression with non-file source map paths ([#4078](https://github.com/evanw/esbuild/issues/4078)) The format of paths in source maps that aren't in the `file` namespace was unintentionally changed in version 0.25.0. Path namespaces is an esbuild-specific concept that is optionally available for plugins to use to distinguish paths from `file` paths and from paths meant for other plugins. Previously the namespace was prepended to the path joined with a `:` character, but version 0.25.0 unintentionally failed to prepend the namespace. The previous behavior has been restored. * Fix a crash with `switch` optimization ([#4088](https://github.com/evanw/esbuild/issues/4088)) The new code in the previous release to optimize dead code in switch statements accidentally introduced a crash in the edge case where one or more switch case values include a function expression. This is because esbuild now visits the case values first to determine whether any cases are dead code, and then visits the case bodies once the dead code status is known. That triggered some internal asserts that guard against traversing the AST in an unexpected order. This crash has been fixed by changing esbuild to expect the new traversal ordering. Here's an example of affected code: ```js switch (x) { case '': return y.map(z => z.value) case y.map(z => z.key).join(','): return [] } ``` * Update Go from 1.23.5 to 1.23.7 ([#4076](https://github.com/evanw/esbuild/issues/4076), [#4077](https://github.com/evanw/esbuild/pull/4077)) This should have no effect on existing code as this version change does not change Go's operating system support. It may remove certain reports from vulnerability scanners that detect which version of the Go compiler esbuild uses. This PR was contributed by [@MikeWillCook](https://github.com/MikeWillCook). ### v0.25.0 **This release deliberately contains backwards-incompatible changes.** To avoid automatically picking up releases like this, you should either be pinning the exact version of `esbuild` in your `package.json` file (recommended) or be using a version range syntax that only accepts patch upgrades such as `^0.24.0` or `~0.24.0`. See npm's documentation about [semver](https://docs.npmjs.com/cli/v6/using-npm/semver/) for more information. * Restrict access to esbuild's development server ([GHSA-67mh-4wv8-2f99](https://github.com/evanw/esbuild/security/advisories/GHSA-67mh-4wv8-2f99)) This change addresses esbuild's first security vulnerability report. Previously esbuild set the `Access-Control-Allow-Origin` header to `*` to allow esbuild's development server to be flexible in how it's used for development. However, this allows the websites you visit to make HTTP requests to esbuild's local development server, which gives read-only access to your source code if the website were to fetch your source code's specific URL. You can read more information in [the report](https://github.com/evanw/esbuild/security/advisories/GHSA-67mh-4wv8-2f99). Starting with this release, [CORS](https://developer.mozilla.org/en-US/docs/Web/HTTP/CORS) will now be disabled, and requests will now be denied if the host does not match the one provided to `--serve=`. The default host is `0.0.0.0`, which refers to all of the IP addresses that represent the local machine (e.g. both `127.0.0.1` and `192.168.0.1`). If you want to customize anything about esbuild's development server, you can [put a proxy in front of esbuild](https://esbuild.github.io/api/#serve-proxy) and modify the incoming and/or outgoing requests. In addition, the `serve()` API call has been changed to return an array of `hosts` instead of a single `host` string. This makes it possible to determine all of the hosts that esbuild's development server will accept. Thanks to [@sapphi-red](https://github.com/sapphi-red) for reporting this issue. * Delete output files when a build fails in watch mode ([#3643](https://github.com/evanw/esbuild/issues/3643)) It has been requested for esbuild to delete files when a build fails in watch mode. Previously esbuild left the old files in place, which could cause people to not immediately realize that the most recent build failed. With this release, esbuild will now delete all output files if a rebuild fails. Fixing the build error and triggering another rebuild will restore all output files again. * Fix correctness issues with the CSS nesting transform ([#3620](https://github.com/evanw/esbuild/issues/3620), [#3877](https://github.com/evanw/esbuild/issues/3877), [#3933](https://github.com/evanw/esbuild/issues/3933), [#3997](https://github.com/evanw/esbuild/issues/3997), [#4005](https://github.com/evanw/esbuild/issues/4005), [#4037](https://github.com/evanw/esbuild/pull/4037), [#4038](https://github.com/evanw/esbuild/pull/4038)) This release fixes the following problems: * Naive expansion of CSS nesting can result in an exponential blow-up of generated CSS if each nesting level has multiple selectors. Previously esbuild sometimes collapsed individual nesting levels using `:is()` to limit expansion. However, this collapsing wasn't correct in some cases, so it has been removed to fix correctness issues. ```css /* Original code */ .parent { > .a, > .b1 > .b2 { color: red; } } /* Old output (with --supported:nesting=false) */ .parent > :is(.a, .b1 > .b2) { color: red; } /* New output (with --supported:nesting=false) */ .parent > .a, .parent > .b1 > .b2 { color: red; } ``` Thanks to [@tim-we](https://github.com/tim-we) for working on a fix. * The `&` CSS nesting selector can be repeated multiple times to increase CSS specificity. Previously esbuild ignored this possibility and incorrectly considered `&&` to have the same specificity as `&`. With this release, this should now work correctly: ```css /* Original code (color should be red) */ div { && { color: red } & { color: blue } } /* Old output (with --supported:nesting=false) */ div { color: red; } div { color: blue; } /* New output (with --supported:nesting=false) */ div:is(div) { color: red; } div { color: blue; } ``` Thanks to [@CPunisher](https://github.com/CPunisher) for working on a fix. * Previously transforming nested CSS incorrectly removed leading combinators from within pseudoclass selectors such as `:where()`. This edge case has been fixed and how has test coverage. ```css /* Original code */ a b:has(> span) { a & { color: green; } } /* Old output (with --supported:nesting=false) */ a :is(a b:has(span)) { color: green; } /* New output (with --supported:nesting=false) */ a :is(a b:has(> span)) { color: green; } ``` This fix was contributed by [@NoremacNergfol](https://github.com/NoremacNergfol). * The CSS minifier contains logic to remove the `&` selector when it can be implied, which happens when there is only one and it's the leading token. However, this logic was incorrectly also applied to selector lists inside of pseudo-class selectors such as `:where()`. With this release, the minifier will now avoid applying this logic in this edge case: ```css /* Original code */ .a { & .b { color: red } :where(& .b) { color: blue } } /* Old output (with --minify) */ .a{.b{color:red}:where(.b){color:#00f}} /* New output (with --minify) */ .a{.b{color:red}:where(& .b){color:#00f}} ``` * Fix some correctness issues with source maps ([#1745](https://github.com/evanw/esbuild/issues/1745), [#3183](https://github.com/evanw/esbuild/issues/3183), [#3613](https://github.com/evanw/esbuild/issues/3613), [#3982](https://github.com/evanw/esbuild/issues/3982)) Previously esbuild incorrectly treated source map path references as file paths instead of as URLs. With this release, esbuild will now treat source map path references as URLs. This fixes the following problems with source maps: * File names in `sourceMappingURL` that contained a space previously did not encode the space as `%20`, which resulted in JavaScript tools (including esbuild) failing to read that path back in when consuming the generated output file. This should now be fixed. * Absolute URLs in `sourceMappingURL` that use the `file://` scheme previously attempted to read from a folder called `file:`. These URLs should now be recognized and parsed correctly. * Entries in the `sources` array in the source map are now treated as URLs instead of file paths. The correct behavior for this is much more clear now that source maps has a [formal specification](https://tc39.es/ecma426/). Many thanks to those who worked on the specification. * Fix incorrect package for `@esbuild/netbsd-arm64` ([#4018](https://github.com/evanw/esbuild/issues/4018)) Due to a copy+paste typo, the binary published to `@esbuild/netbsd-arm64` was not actually for `arm64`, and didn't run in that environment. This release should fix running esbuild in that environment (NetBSD on 64-bit ARM). Sorry about the mistake. * Fix a minification bug with bitwise operators and bigints ([#4065](https://github.com/evanw/esbuild/issues/4065)) This change removes an incorrect assumption in esbuild that all bitwise operators result in a numeric integer. That assumption was correct up until the introduction of bigints in ES2020, but is no longer correct because almost all bitwise operators now operate on both numbers and bigints. Here's an example of the incorrect minification: ```js // Original code if ((a & b) !== 0) found = true // Old output (with --minify) a&b&&(found=!0); // New output (with --minify) (a&b)!==0&&(found=!0); ``` * Fix esbuild incorrectly rejecting valid TypeScript edge case ([#4027](https://github.com/evanw/esbuild/issues/4027)) The following TypeScript code is valid: ```ts export function open(async?: boolean): void { console.log(async as boolean) } ``` Before this version, esbuild would fail to parse this with a syntax error as it expected the token sequence `async as ...` to be the start of an async arrow function expression `async as => ...`. This edge case should be parsed correctly by esbuild starting with this release. * Transform BigInt values into constructor calls when unsupported ([#4049](https://github.com/evanw/esbuild/issues/4049)) Previously esbuild would refuse to compile the BigInt literals (such as `123n`) if they are unsupported in the configured target environment (such as with `--target=es6`). The rationale was that they cannot be polyfilled effectively because they change the behavior of JavaScript's arithmetic operators and JavaScript doesn't have operator overloading. However, this prevents using esbuild with certain libraries that would otherwise work if BigInt literals were ignored, such as with old versions of the [`buffer` library](https://github.com/feross/buffer) before the library fixed support for running in environments without BigInt support. So with this release, esbuild will now turn BigInt literals into BigInt constructor calls (so `123n` becomes `BigInt(123)`) and generate a warning in this case. You can turn off the warning with `--log-override:bigint=silent` or restore the warning to an error with `--log-override:bigint=error` if needed. * Change how `console` API dropping works ([#4020](https://github.com/evanw/esbuild/issues/4020)) Previously the `--drop:console` feature replaced all method calls off of the `console` global with `undefined` regardless of how long the property access chain was (so it applied to `console.log()` and `console.log.call(console)` and `console.log.not.a.method()`). However, it was pointed out that this breaks uses of `console.log.bind(console)`. That's also incompatible with Terser's implementation of the feature, which is where this feature originally came from (it does support `bind`). So with this release, using this feature with esbuild will now only replace one level of method call (unless extended by `call` or `apply`) and will replace the method being called with an empty function in complex cases: ```js // Original code const x = console.log('x') const y = console.log.call(console, 'y') const z = console.log.bind(console)('z') // Old output (with --drop-console) const x = void 0; const y = void 0; const z = (void 0)("z"); // New output (with --drop-console) const x = void 0; const y = void 0; const z = (() => { }).bind(console)("z"); ``` This should more closely match Terser's existing behavior. * Allow BigInt literals as `define` values With this release, you can now use BigInt literals as define values, such as with `--define:FOO=123n`. Previously trying to do this resulted in a syntax error. * Fix a bug with resolve extensions in `node_modules` ([#4053](https://github.com/evanw/esbuild/issues/4053)) The `--resolve-extensions=` option lets you specify the order in which to try resolving implicit file extensions. For complicated reasons, esbuild reorders TypeScript file extensions after JavaScript ones inside of `node_modules` so that JavaScript source code is always preferred to TypeScript source code inside of dependencies. However, this reordering had a bug that could accidentally change the relative order of TypeScript file extensions if one of them was a prefix of the other. That bug has been fixed in this release. You can see the issue for details. * Better minification of statically-determined `switch` cases ([#4028](https://github.com/evanw/esbuild/issues/4028)) With this release, esbuild will now try to trim unused code within `switch` statements when the test expression and `case` expressions are primitive literals. This can arise when the test expression is an identifier that is substituted for a primitive literal at compile time. For example: ```js // Original code switch (MODE) { case 'dev': installDevToolsConsole() break case 'prod': return default: throw new Error } // Old output (with --minify '--define:MODE="prod"') switch("prod"){case"dev":installDevToolsConsole();break;case"prod":return;default:throw new Error} // New output (with --minify '--define:MODE="prod"') return; ``` * Emit `/* @__KEY__ */` for string literals derived from property names ([#4034](https://github.com/evanw/esbuild/issues/4034)) Property name mangling is an advanced feature that shortens certain property names for better minification (I say "advanced feature" because it's very easy to break your code with it). Sometimes you need to store a property name in a string, such as `obj.get('foo')` instead of `obj.foo`. JavaScript minifiers such as esbuild and [Terser](https://terser.org/) have a convention where a `/* @__KEY__ */` comment before the string makes it behave like a property name. So `obj.get(/* @__KEY__ */ 'foo')` allows the contents of the string `'foo'` to be shortened. However, esbuild sometimes itself generates string literals containing property names when transforming code, such as when lowering class fields to ES6 or when transforming TypeScript decorators. Previously esbuild didn't generate its own `/* @__KEY__ */` comments in this case, which means that minifying your code by running esbuild again on its own output wouldn't work correctly (this does not affect people that both minify and transform their code in a single step). With this release, esbuild will now generate `/* @__KEY__ */` comments for property names in generated string literals. To avoid lots of unnecessary output for people that don't use this advanced feature, the generated comments will only be present when the feature is active. If you want to generate the comments but not actually mangle any property names, you can use a flag that has no effect such as `--reserve-props=.`, which tells esbuild to not mangle any property names (but still activates this feature). * The `text` loader now strips the UTF-8 BOM if present ([#3935](https://github.com/evanw/esbuild/issues/3935)) Some software (such as Notepad on Windows) can create text files that start with the three bytes `0xEF 0xBB 0xBF`, which is referred to as the "byte order mark". This prefix is intended to be removed before using the text. Previously esbuild's `text` loader included this byte sequence in the string, which turns into a prefix of `\uFEFF` in a JavaScript string when decoded from UTF-8. With this release, esbuild's `text` loader will now remove these bytes when they occur at the start of the file. * Omit legal comment output files when empty ([#3670](https://github.com/evanw/esbuild/issues/3670)) Previously configuring esbuild with `--legal-comment=external` or `--legal-comment=linked` would always generate a `.LEGAL.txt` output file even if it was empty. Starting with this release, esbuild will now only do this if the file will be non-empty. This should result in a more organized output directory in some cases. * Update Go from 1.23.1 to 1.23.5 ([#4056](https://github.com/evanw/esbuild/issues/4056), [#4057](https://github.com/evanw/esbuild/pull/4057)) This should have no effect on existing code as this version change does not change Go's operating system support. It may remove certain reports from vulnerability scanners that detect which version of the Go compiler esbuild uses. This PR was contributed by [@MikeWillCook](https://github.com/MikeWillCook). * Allow passing a port of 0 to the development server ([#3692](https://github.com/evanw/esbuild/issues/3692)) Unix sockets interpret a port of 0 to mean "pick a random unused port in the [ephemeral port](https://en.wikipedia.org/wiki/Ephemeral_port) range". However, esbuild's default behavior when the port is not specified is to pick the first unused port starting from 8000 and upward. This is more convenient because port 8000 is typically free, so you can for example restart the development server and reload your app in the browser without needing to change the port in the URL. Since esbuild is written in Go (which does not have optional fields like JavaScript), not specifying the port in Go means it defaults to 0, so previously passing a port of 0 to esbuild caused port 8000 to be picked. Starting with this release, passing a port of 0 to esbuild when using the CLI or the JS API will now pass port 0 to the OS, which will pick a random ephemeral port. To make this possible, the `Port` option in the Go API has been changed from `uint16` to `int` (to allow for additional sentinel values) and passing a port of -1 in Go now picks a random port. Both the CLI and JS APIs now remap an explicitly-provided port of 0 into -1 for the internal Go API. Another option would have been to change `Port` in Go from `uint16` to `*uint16` (Go's closest equivalent of `number | undefined`). However, that would make the common case of providing an explicit port in Go very awkward as Go doesn't support taking the address of integer constants. This tradeoff isn't worth it as picking a random ephemeral port is a rare use case. So the CLI and JS APIs should now match standard Unix behavior when the port is 0, but you need to use -1 instead with Go API. * Minification now avoids inlining constants with direct `eval` ([#4055](https://github.com/evanw/esbuild/issues/4055)) Direct `eval` can be used to introduce a new variable like this: ```js const variable = false ;(function () { eval("var variable = true") console.log(variable) })() ``` Previously esbuild inlined `variable` here (which became `false`), which changed the behavior of the code. This inlining is now avoided, but please keep in mind that direct `eval` breaks many assumptions that JavaScript tools hold about normal code (especially when bundling) and I do not recommend using it. There are usually better alternatives that have a more localized impact on your code. You can read more about this here: https://esbuild.github.io/link/direct-eval/ ### v0.24.2 * Fix regression with `--define` and `import.meta` ([#4010](https://github.com/evanw/esbuild/issues/4010), [#4012](https://github.com/evanw/esbuild/issues/4012), [#4013](https://github.com/evanw/esbuild/pull/4013)) The previous change in version 0.24.1 to use a more expression-like parser for `define` values to allow quoted property names introduced a regression that removed the ability to use `--define:import.meta=...`. Even though `import` is normally a keyword that can't be used as an identifier, ES modules special-case the `import.meta` expression to behave like an identifier anyway. This change fixes the regression. This fix was contributed by [@sapphi-red](https://github.com/sapphi-red). ### v0.24.1 * Allow `es2024` as a target in `tsconfig.json` ([#4004](https://github.com/evanw/esbuild/issues/4004)) TypeScript recently [added `es2024`](https://devblogs.microsoft.com/typescript/announcing-typescript-5-7/#support-for---target-es2024-and---lib-es2024) as a compilation target, so esbuild now supports this in the `target` field of `tsconfig.json` files, such as in the following configuration file: ```json { "compilerOptions": { "target": "ES2024" } } ``` As a reminder, the only thing that esbuild uses this field for is determining whether or not to use legacy TypeScript behavior for class fields. You can read more in [the documentation](https://esbuild.github.io/content-types/#tsconfig-json). This fix was contributed by [@billyjanitsch](https://github.com/billyjanitsch). * Allow automatic semicolon insertion after `get`/`set` This change fixes a grammar bug in the parser that incorrectly treated the following code as a syntax error: ```ts class Foo { get *x() {} set *y() {} } ``` The above code will be considered valid starting with this release. This change to esbuild follows a [similar change to TypeScript](https://github.com/microsoft/TypeScript/pull/60225) which will allow this syntax starting with TypeScript 5.7. * Allow quoted property names in `--define` and `--pure` ([#4008](https://github.com/evanw/esbuild/issues/4008)) The `define` and `pure` API options now accept identifier expressions containing quoted property names. Previously all identifiers in the identifier expression had to be bare identifiers. This change now makes `--define` and `--pure` consistent with `--global-name`, which already supported quoted property names. For example, the following is now possible: ```js // The following code now transforms to "return true;\n" console.log(esbuild.transformSync( `return process.env['SOME-TEST-VAR']`, { define: { 'process.env["SOME-TEST-VAR"]': 'true' } }, )) ``` Note that if you're passing values like this on the command line using esbuild's `--define` flag, then you'll need to know how to escape quote characters for your shell. You may find esbuild's JavaScript API more ergonomic and portable than writing shell code. * Minify empty `try`/`catch`/`finally` blocks ([#4003](https://github.com/evanw/esbuild/issues/4003)) With this release, esbuild will now attempt to minify empty `try` blocks: ```js // Original code try {} catch { foo() } finally { bar() } // Old output (with --minify) try{}catch{foo()}finally{bar()} // New output (with --minify) bar(); ``` This can sometimes expose additional minification opportunities. * Include `entryPoint` metadata for the `copy` loader ([#3985](https://github.com/evanw/esbuild/issues/3985)) Almost all entry points already include a `entryPoint` field in the `outputs` map in esbuild's build metadata. However, this wasn't the case for the `copy` loader as that loader is a special-case that doesn't behave like other loaders. This release adds the `entryPoint` field in this case. * Source mappings may now contain `null` entries ([#3310](https://github.com/evanw/esbuild/issues/3310), [#3878](https://github.com/evanw/esbuild/issues/3878)) With this change, sources that result in an empty source map may now emit a `null` source mapping (i.e. one with a generated position but without a source index or original position). This change improves source map accuracy by fixing a problem where minified code from a source without any source mappings could potentially still be associated with a mapping from another source file earlier in the generated output on the same minified line. It manifests as nonsensical files in source mapped stack traces. Now the `null` mapping "resets" the source map so that any lookups into the minified code without any mappings resolves to `null` (which appears as the output file in stack traces) instead of the incorrect source file. This change shouldn't affect anything in most situations. I'm only mentioning it in the release notes in case it introduces a bug with source mapping. It's part of a work-in-progress future feature that will let you omit certain unimportant files from the generated source map to reduce source map size. * Avoid using the parent directory name for determinism ([#3998](https://github.com/evanw/esbuild/issues/3998)) To make generated code more readable, esbuild includes the name of the source file when generating certain variable names within the file. Specifically bundling a CommonJS file generates a variable to store the lazily-evaluated module initializer. However, if a file is named `index.js` (or with a different extension), esbuild will use the name of the parent directory instead for a better name (since many packages have files all named `index.js` but have unique directory names). This is problematic when the bundle entry point is named `index.js` and the parent directory name is non-deterministic (e.g. a temporary directory created by a build script). To avoid non-determinism in esbuild's output, esbuild will now use `index` instead of the parent directory in this case. Specifically this will happen if the parent directory is equal to esbuild's `outbase` API option, which defaults to the [lowest common ancestor](https://en.wikipedia.org/wiki/Lowest_common_ancestor) of all user-specified entry point paths. * Experimental support for esbuild on NetBSD ([#3974](https://github.com/evanw/esbuild/pull/3974)) With this release, esbuild now has a published binary executable for [NetBSD](https://www.netbsd.org/) in the [`@esbuild/netbsd-arm64`](https://www.npmjs.com/package/@esbuild/netbsd-arm64) npm package, and esbuild's installer has been modified to attempt to use it when on NetBSD. Hopefully this makes installing esbuild via npm work on NetBSD. This change was contributed by [@bsiegert](https://github.com/bsiegert). ⚠️ Note: NetBSD is not one of [Node's supported platforms](https://nodejs.org/api/process.html#process_process_platform), so installing esbuild may or may not work on NetBSD depending on how Node has been patched. This is not a problem with esbuild. ⚠️ ### v0.24.0 **_This release deliberately contains backwards-incompatible changes._** To avoid automatically picking up releases like this, you should either be pinning the exact version of `esbuild` in your `package.json` file (recommended) or be using a version range syntax that only accepts patch upgrades such as `^0.23.0` or `~0.23.0`. See npm's documentation about [semver](https://docs.npmjs.com/cli/v6/using-npm/semver/) for more information. * Drop support for older platforms ([#3902](https://github.com/evanw/esbuild/pull/3902)) This release drops support for the following operating system: * macOS 10.15 Catalina This is because the Go programming language dropped support for this operating system version in Go 1.23, and this release updates esbuild from Go 1.22 to Go 1.23. Go 1.23 now requires macOS 11 Big Sur or later. Note that this only affects the binary esbuild executables that are published to the esbuild npm package. It's still possible to compile esbuild's source code for these older operating systems. If you need to, you can compile esbuild for yourself using an older version of the Go compiler (before Go version 1.23). That might look something like this: ``` git clone https://github.com/evanw/esbuild.git cd esbuild go build ./cmd/esbuild ./esbuild --version ``` * Fix class field decorators in TypeScript if `useDefineForClassFields` is `false` ([#3913](https://github.com/evanw/esbuild/issues/3913)) Setting the `useDefineForClassFields` flag to `false` in `tsconfig.json` means class fields use the legacy TypeScript behavior instead of the standard JavaScript behavior. Specifically they use assign semantics instead of define semantics (e.g. setters are triggered) and fields without an initializer are not initialized at all. However, when this legacy behavior is combined with standard JavaScript decorators, TypeScript switches to always initializing all fields, even those without initializers. Previously esbuild incorrectly continued to omit field initializers for this edge case. These field initializers in this case should now be emitted starting with this release. * Avoid incorrect cycle warning with `tsconfig.json` multiple inheritance ([#3898](https://github.com/evanw/esbuild/issues/3898)) TypeScript 5.0 introduced multiple inheritance for `tsconfig.json` files where `extends` can be an array of file paths. Previously esbuild would incorrectly treat files encountered more than once when processing separate subtrees of the multiple inheritance hierarchy as an inheritance cycle. With this release, `tsconfig.json` files containing this edge case should work correctly without generating a warning. * Handle Yarn Plug'n'Play stack overflow with `tsconfig.json` ([#3915](https://github.com/evanw/esbuild/issues/3915)) Previously a `tsconfig.json` file that `extends` another file in a package with an `exports` map could cause a stack overflow when Yarn's Plug'n'Play resolution was active. This edge case should work now starting with this release. * Work around more issues with Deno 1.31+ ([#3917](https://github.com/evanw/esbuild/pull/3917)) This version of Deno broke the `stdin` and `stdout` properties on command objects for inherited streams, which matters when you run esbuild's Deno module as the entry point (i.e. when `import.meta.main` is `true`). Previously esbuild would crash in Deno 1.31+ if you ran esbuild like that. This should be fixed starting with this release. This fix was contributed by [@Joshix-1](https://github.com/Joshix-1). ### v0.23.1 * Allow using the `node:` import prefix with `es*` targets ([#3821](https://github.com/evanw/esbuild/issues/3821)) The [`node:` prefix on imports](https://nodejs.org/api/esm.html#node-imports) is an alternate way to import built-in node modules. For example, `import fs from "fs"` can also be written `import fs from "node:fs"`. This only works with certain newer versions of node, so esbuild removes it when you target older versions of node such as with `--target=node14` so that your code still works. With the way esbuild's platform-specific feature compatibility table works, this was added by saying that only newer versions of node support this feature. However, that means that a target such as `--target=node18,es2022` removes the `node:` prefix because none of the `es*` targets are known to support this feature. This release adds the support for the `node:` flag to esbuild's internal compatibility table for `es*` to allow you to use compound targets like this: ```js // Original code import fs from 'node:fs' fs.open // Old output (with --bundle --format=esm --platform=node --target=node18,es2022) import fs from "fs"; fs.open; // New output (with --bundle --format=esm --platform=node --target=node18,es2022) import fs from "node:fs"; fs.open; ``` * Fix a panic when using the CLI with invalid build flags if `--analyze` is present ([#3834](https://github.com/evanw/esbuild/issues/3834)) Previously esbuild's CLI could crash if it was invoked with flags that aren't valid for a "build" API call and the `--analyze` flag is present. This was caused by esbuild's internals attempting to add a Go plugin (which is how `--analyze` is implemented) to a null build object. The panic has been fixed in this release. * Fix incorrect location of certain error messages ([#3845](https://github.com/evanw/esbuild/issues/3845)) This release fixes a regression that caused certain errors relating to variable declarations to be reported at an incorrect location. The regression was introduced in version 0.18.7 of esbuild. * Print comments before case clauses in switch statements ([#3838](https://github.com/evanw/esbuild/issues/3838)) With this release, esbuild will attempt to print comments that come before case clauses in switch statements. This is similar to what esbuild already does for comments inside of certain types of expressions. Note that these types of comments are not printed if minification is enabled (specifically whitespace minification). * Fix a memory leak with `pluginData` ([#3825](https://github.com/evanw/esbuild/issues/3825)) With this release, the build context's internal `pluginData` cache will now be cleared when starting a new build. This should fix a leak of memory from plugins that return `pluginData` objects from `onResolve` and/or `onLoad` callbacks. ### v0.23.0 **_This release deliberately contains backwards-incompatible changes._** To avoid automatically picking up releases like this, you should either be pinning the exact version of `esbuild` in your `package.json` file (recommended) or be using a version range syntax that only accepts patch upgrades such as `^0.22.0` or `~0.22.0`. See npm's documentation about [semver](https://docs.npmjs.com/cli/v6/using-npm/semver/) for more information. * Revert the recent change to avoid bundling dependencies for node ([#3819](https://github.com/evanw/esbuild/issues/3819)) This release reverts the recent change in version 0.22.0 that made `--packages=external` the default behavior with `--platform=node`. The default is now back to `--packages=bundle`. I've just been made aware that Amazon doesn't pin their dependencies in their "AWS CDK" product, which means that whenever esbuild publishes a new release, many people (potentially everyone?) using their SDK around the world instantly starts using it without Amazon checking that it works first. This change in version 0.22.0 happened to break their SDK. I'm amazed that things haven't broken before this point. This revert attempts to avoid these problems for Amazon's customers. Hopefully Amazon will pin their dependencies in the future. In addition, this is probably a sign that esbuild is used widely enough that it now needs to switch to a more complicated release model. I may have esbuild use a beta channel model for further development. * Fix preserving collapsed JSX whitespace ([#3818](https://github.com/evanw/esbuild/issues/3818)) When transformed, certain whitespace inside JSX elements is ignored completely if it collapses to an empty string. However, the whitespace should only be ignored if the JSX is being transformed, not if it's being preserved. This release fixes a bug where esbuild was previously incorrectly ignoring collapsed whitespace with `--jsx=preserve`. Here is an example: ```jsx // Original code <Foo> <Bar /> </Foo> // Old output (with --jsx=preserve) <Foo><Bar /></Foo>; // New output (with --jsx=preserve) <Foo> <Bar /> </Foo>; ``` ### v0.22.0 **This release deliberately contains backwards-incompatible changes.** To avoid automatically picking up releases like this, you should either be pinning the exact version of `esbuild` in your `package.json` file (recommended) or be using a version range syntax that only accepts patch upgrades such as `^0.21.0` or `~0.21.0`. See npm's documentation about [semver](https://docs.npmjs.com/cli/v6/using-npm/semver/) for more information. * Omit packages from bundles by default when targeting node ([#1874](https://github.com/evanw/esbuild/issues/1874), [#2830](https://github.com/evanw/esbuild/issues/2830), [#2846](https://github.com/evanw/esbuild/issues/2846), [#2915](https://github.com/evanw/esbuild/issues/2915), [#3145](https://github.com/evanw/esbuild/issues/3145), [#3294](https://github.com/evanw/esbuild/issues/3294), [#3323](https://github.com/evanw/esbuild/issues/3323), [#3582](https://github.com/evanw/esbuild/issues/3582), [#3809](https://github.com/evanw/esbuild/issues/3809), [#3815](https://github.com/evanw/esbuild/issues/3815)) This breaking change is an experiment. People are commonly confused when using esbuild to bundle code for node (i.e. for `--platform=node`) because some packages may not be intended for bundlers, and may use node-specific features that don't work with a bundler. Even though esbuild's "getting started" instructions say to use `--packages=external` to work around this problem, many people don't read the documentation and don't do this, and are then confused when it doesn't work. So arguably this is a bad default behavior for esbuild to have if people keep tripping over this. With this release, esbuild will now omit packages from the bundle by default when the platform is `node` (i.e. the previous behavior of `--packages=external` is now the default in this case). _Note that your dependencies must now be present on the file system when your bundle is run._ If you don't want this behavior, you can do `--packages=bundle` to allow packages to be included in the bundle (i.e. the previous default behavior). Note that `--packages=bundle` doesn't mean all packages are bundled, just that packages are allowed to be bundled. You can still exclude individual packages from the bundle using `--external:` even when `--packages=bundle` is present. The `--packages=` setting considers all import paths that "look like" package imports in the original source code to be package imports. Specifically import paths that don't start with a path segment of `/` or `.` or `..` are considered to be package imports. The only two exceptions to this rule are [subpath imports](https://nodejs.org/api/packages.html#subpath-imports) (which start with a `#` character) and TypeScript path remappings via `paths` and/or `baseUrl` in `tsconfig.json` (which are applied first). * Drop support for older platforms ([#3802](https://github.com/evanw/esbuild/issues/3802)) This release drops support for the following operating systems: * Windows 7 * Windows 8 * Windows Server 2008 * Windows Server 2012 This is because the Go programming language dropped support for these operating system versions in [Go 1.21](https://go.dev/doc/go1.21#windows), and this release updates esbuild from Go 1.20 to Go 1.22. Note that this only affects the binary esbuild executables that are published to the `esbuild` npm package. It's still possible to compile esbuild's source code for these older operating systems. If you need to, you can compile esbuild for yourself using an older version of the Go compiler (before Go version 1.21). That might look something like this: ``` git clone https://github.com/evanw/esbuild.git cd esbuild go build ./cmd/esbuild ./esbuild.exe --version ``` In addition, this release increases the minimum required node version for esbuild's JavaScript API from node 12 to node 18. Node 18 is the oldest version of node that is still being supported (see node's [release schedule](https://nodejs.org/en/about/previous-releases) for more information). This increase is because of an incompatibility between the JavaScript that the Go compiler generates for the `esbuild-wasm` package and versions of node before node 17.4 (specifically the `crypto.getRandomValues` function). * Update `await using` behavior to match TypeScript TypeScript 5.5 subtly changes the way `await using` behaves. This release updates esbuild to match these changes in TypeScript. You can read more about these changes in [microsoft/TypeScript#58624](https://github.com/microsoft/TypeScript/pull/58624). * Allow `es2024` as a target environment The ECMAScript 2024 specification was just approved, so it has been added to esbuild as a possible compilation target. You can read more about the features that it adds here: [https://2ality.com/2024/06/ecmascript-2024.html](https://2ality.com/2024/06/ecmascript-2024.html). The only addition that's relevant for esbuild is the regular expression `/v` flag. With `--target=es2024`, regular expressions that use the `/v` flag will now be passed through untransformed instead of being transformed into a call to `new RegExp`. * Publish binaries for OpenBSD on 64-bit ARM ([#3665](https://github.com/evanw/esbuild/issues/3665), [#3674](https://github.com/evanw/esbuild/pull/3674)) With this release, you should now be able to install the `esbuild` npm package in OpenBSD on 64-bit ARM, such as on an Apple device with an M1 chip. This was contributed by [@ikmckenz](https://github.com/ikmckenz). * Publish binaries for WASI (WebAssembly System Interface) preview 1 ([#3300](https://github.com/evanw/esbuild/issues/3300), [#3779](https://github.com/evanw/esbuild/pull/3779)) The upcoming WASI (WebAssembly System Interface) standard is going to be a way to run WebAssembly outside of a JavaScript host environment. In this scenario you only need a `.wasm` file without any supporting JavaScript code. Instead of JavaScript providing the APIs for the host environment, the WASI standard specifies a "system interface" that WebAssembly code can access directly (e.g. for file system access). Development versions of the WASI specification are being released using preview numbers. The people behind WASI are currently working on preview 2 but the Go compiler has [released support for preview 1](https://go.dev/blog/wasi), which from what I understand is now considered an unsupported legacy release. However, some people have requested that esbuild publish binary executables that support WASI preview 1 so they can experiment with them. This release publishes esbuild precompiled for WASI preview 1 to the `@esbuild/wasi-preview1` package on npm (specifically the file `@esbuild/wasi-preview1/esbuild.wasm`). This binary executable has not been tested and won't be officially supported, as it's for an old preview release of a specification that has since moved in another direction. If it works for you, great! If not, then you'll likely have to wait for the ecosystem to evolve before using esbuild with WASI. For example, it sounds like perhaps WASI preview 1 doesn't include support for opening network sockets so esbuild's local development server is unlikely to work with WASI preview 1. * Warn about `onResolve` plugins not setting a path ([#3790](https://github.com/evanw/esbuild/issues/3790)) Plugins that return values from `onResolve` without resolving the path (i.e. without setting either `path` or `external: true`) will now cause a warning. This is because esbuild only uses return values from `onResolve` if it successfully resolves the path, and it's not good for invalid input to be silently ignored. * Add a new Go API for running the CLI with plugins ([#3539](https://github.com/evanw/esbuild/pull/3539)) With esbuild's Go API, you can now call `cli.RunWithPlugins(args, plugins)` to pass an array of esbuild plugins to be used during the build process. This allows you to create a CLI that behaves similarly to esbuild's CLI but with additional Go plugins enabled. This was contributed by [@edewit](https://github.com/edewit). ### v0.21.5 * Fix `Symbol.metadata` on classes without a class decorator ([#3781](https://github.com/evanw/esbuild/issues/3781)) This release fixes a bug with esbuild's support for the [decorator metadata proposal](https://github.com/tc39/proposal-decorator-metadata). Previously esbuild only added the `Symbol.metadata` property to decorated classes if there was a decorator on the class element itself. However, the proposal says that the `Symbol.metadata` property should be present on all classes that have any decorators at all, not just those with a decorator on the class element itself. * Allow unknown import attributes to be used with the `copy` loader ([#3792](https://github.com/evanw/esbuild/issues/3792)) Import attributes (the `with` keyword on `import` statements) are allowed to alter how that path is loaded. For example, esbuild cannot assume that it knows how to load `./bagel.js` as type `bagel`: ```js // This is an error with "--bundle" without also using "--external:./bagel.js" import tasty from "./bagel.js" with { type: "bagel" } ``` Because of that, bundling this code with esbuild is an error unless the file `./bagel.js` is external to the bundle (such as with `--bundle --external:./bagel.js`). However, there is an additional case where it's ok for esbuild to allow this: if the file is loaded using the `copy` loader. That's because the `copy` loader behaves similarly to `--external` in that the file is left external to the bundle. The difference is that the `copy` loader copies the file into the output folder and rewrites the import path while `--external` doesn't. That means the following will now work with the `copy` loader (such as with `--bundle --loader:.bagel=copy`): ```js // This is no longer an error with "--bundle" and "--loader:.bagel=copy" import tasty from "./tasty.bagel" with { type: "bagel" } ``` * Support import attributes with glob-style imports ([#3797](https://github.com/evanw/esbuild/issues/3797)) This release adds support for import attributes (the `with` option) to glob-style imports (dynamic imports with certain string literal patterns as paths). These imports previously didn't support import attributes due to an oversight. So code like this will now work correctly: ```ts async function loadLocale(locale: string): Locale { const data = await import(`./locales/${locale}.data`, { with: { type: 'json' } }) return unpackLocale(locale, data) } ``` Previously this didn't work even though esbuild normally supports forcing the JSON loader using an import attribute. Attempting to do this used to result in the following error: ``` ✘ [ERROR] No loader is configured for ".data" files: locales/en-US.data example.ts:2:28: 2 │ const data = await import(`./locales/${locale}.data`, { with: { type: 'json' } }) ╵ ~~~~~~~~~~~~~~~~~~~~~~~~~~ ``` In addition, this change means plugins can now access the contents of `with` for glob-style imports. * Support `${configDir}` in `tsconfig.json` files ([#3782](https://github.com/evanw/esbuild/issues/3782)) This adds support for a new feature from the upcoming TypeScript 5.5 release. The character sequence `${configDir}` is now respected at the start of `baseUrl` and `paths` values, which are used by esbuild during bundling to correctly map import paths to file system paths. This feature lets base `tsconfig.json` files specified via `extends` refer to the directory of the top-level `tsconfig.json` file. Here is an example: ```json { "compilerOptions": { "paths": { "js/*": ["${configDir}/dist/js/*"] } } } ``` You can read more in [TypeScript's blog post about their upcoming 5.5 release](https://devblogs.microsoft.com/typescript/announcing-typescript-5-5-rc/#the-configdir-template-variable-for-configuration-files). Note that this feature does not make use of template literals (you need to use `"${configDir}/dist/js/*"` not `` `${configDir}/dist/js/*` ``). The syntax for `tsconfig.json` is still just JSON with comments, and JSON syntax does not allow template literals. This feature only recognizes `${configDir}` in strings for certain path-like properties, and only at the beginning of the string. * Fix internal error with `--supported:object-accessors=false` ([#3794](https://github.com/evanw/esbuild/issues/3794)) This release fixes a regression in 0.21.0 where some code that was added to esbuild's internal runtime library of helper functions for JavaScript decorators fails to parse when you configure esbuild with `--supported:object-accessors=false`. The reason is that esbuild introduced code that does `{ get [name]() {} }` which uses both the `object-extensions` feature for the `[name]` and the `object-accessors` feature for the `get`, but esbuild was incorrectly only checking for `object-extensions` and not for `object-accessors`. Additional tests have been added to avoid this type of issue in the future. A workaround for this issue in earlier releases is to also add `--supported:object-extensions=false`. ### v0.21.4 * Update support for import assertions and import attributes in node ([#3778](https://github.com/evanw/esbuild/issues/3778)) Import assertions (the `assert` keyword) have been removed from node starting in v22.0.0. So esbuild will now strip them and generate a warning with `--target=node22` or above: ``` ▲ [WARNING] The "assert" keyword is not supported in the configured target environment ("node22") [assert-to-with] example.mjs:1:40: 1 │ import json from "esbuild/package.json" assert { type: "json" } │ ~~~~~~ ╵ with Did you mean to use "with" instead of "assert"? ``` Import attributes (the `with` keyword) have been backported to node 18 starting in v18.20.0. So esbuild will no longer strip them with `--target=node18.N` if `N` is 20 or greater. * Fix `for await` transform when a label is present This release fixes a bug where the `for await` transform, which wraps the loop in a `try` statement, previously failed to also move the loop's label into the `try` statement. This bug only affects code that uses both of these features in combination. Here's an example of some affected code: ```js // Original code async function test() { outer: for await (const x of [Promise.resolve([0, 1])]) { for (const y of x) if (y) break outer throw 'fail' } } // Old output (with --target=es6) function test() { return __async(this, null, function* () { outer: try { for (var iter = __forAwait([Promise.resolve([0, 1])]), more, temp, error; more = !(temp = yield iter.next()).done; more = false) { const x = temp.value; for (const y of x) if (y) break outer; throw "fail"; } } catch (temp) { error = [temp]; } finally { try { more && (temp = iter.return) && (yield temp.call(iter)); } finally { if (error) throw error[0]; } } }); } // New output (with --target=es6) function test() { return __async(this, null, function* () { try { outer: for (var iter = __forAwait([Promise.resolve([0, 1])]), more, temp, error; more = !(temp = yield iter.next()).done; more = false) { const x = temp.value; for (const y of x) if (y) break outer; throw "fail"; } } catch (temp) { error = [temp]; } finally { try { more && (temp = iter.return) && (yield temp.call(iter)); } finally { if (error) throw error[0]; } } }); } ``` * Do additional constant folding after cross-module enum inlining ([#3416](https://github.com/evanw/esbuild/issues/3416), [#3425](https://github.com/evanw/esbuild/issues/3425)) This release adds a few more cases where esbuild does constant folding after cross-module enum inlining. ```ts // Original code: enum.ts export enum Platform { WINDOWS = 'windows', MACOS = 'macos', LINUX = 'linux', } // Original code: main.ts import { Platform } from './enum'; declare const PLATFORM: string; export function logPlatform() { if (PLATFORM == Platform.WINDOWS) console.log('Windows'); else if (PLATFORM == Platform.MACOS) console.log('macOS'); else if (PLATFORM == Platform.LINUX) console.log('Linux'); else console.log('Other'); } // Old output (with --bundle '--define:PLATFORM="macos"' --minify --format=esm) function n(){"windows"=="macos"?console.log("Windows"):"macos"=="macos"?console.log("macOS"):"linux"=="macos"?console.log("Linux"):console.log("Other")}export{n as logPlatform}; // New output (with --bundle '--define:PLATFORM="macos"' --minify --format=esm) function n(){console.log("macOS")}export{n as logPlatform}; ``` * Pass import attributes to on-resolve plugins ([#3384](https://github.com/evanw/esbuild/issues/3384), [#3639](https://github.com/evanw/esbuild/issues/3639), [#3646](https://github.com/evanw/esbuild/issues/3646)) With this release, on-resolve plugins will now have access to the import attributes on the import via the `with` property of the arguments object. This mirrors the `with` property of the arguments object that's already passed to on-load plugins. In addition, you can now pass `with` to the `resolve()` API call which will then forward that value on to all relevant plugins. Here's an example of a plugin that can now be written: ```js const examplePlugin = { name: 'Example plugin', setup(build) { build.onResolve({ filter: /.*/ }, args => { if (args.with.type === 'external') return { external: true } }) } } require('esbuild').build({ stdin: { contents: ` import foo from "./foo" with { type: "external" } foo() `, }, bundle: true, format: 'esm', write: false, plugins: [examplePlugin], }).then(result => { console.log(result.outputFiles[0].text) }) ``` * Formatting support for the `@position-try` rule ([#3773](https://github.com/evanw/esbuild/issues/3773)) Chrome shipped this new CSS at-rule in version 125 as part of the [CSS anchor positioning API](https://developer.chrome.com/blog/anchor-positioning-api). With this release, esbuild now knows to expect a declaration list inside of the `@position-try` body block and will format it appropriately. * Always allow internal string import and export aliases ([#3343](https://github.com/evanw/esbuild/issues/3343)) Import and export names can be string literals in ES2022+. Previously esbuild forbid any usage of these aliases when the target was below ES2022. Starting with this release, esbuild will only forbid such usage when the alias would otherwise end up in output as a string literal. String literal aliases that are only used internally in the bundle and are "compiled away" are no longer errors. This makes it possible to use string literal aliases with esbuild's `inject` feature even when the target is earlier than ES2022. ### v0.21.3 * Implement the decorator metadata proposal ([#3760](https://github.com/evanw/esbuild/issues/3760)) This release implements the [decorator metadata proposal](https://github.com/tc39/proposal-decorator-metadata), which is a sub-proposal of the [decorators proposal](https://github.com/tc39/proposal-decorators). Microsoft shipped the decorators proposal in [TypeScript 5.0](https://devblogs.microsoft.com/typescript/announcing-typescript-5-0/#decorators) and the decorator metadata proposal in [TypeScript 5.2](https://devblogs.microsoft.com/typescript/announcing-typescript-5-2/#decorator-metadata), so it's important that esbuild also supports both of these features. Here's a quick example: ```js // Shim the "Symbol.metadata" symbol Symbol.metadata ??= Symbol('Symbol.metadata') const track = (_, context) => { (context.metadata.names ||= []).push(context.name) } class Foo { @track foo = 1 @track bar = 2 } // Prints ["foo", "bar"] console.log(Foo[Symbol.metadata].names) ``` **⚠️ WARNING ⚠️** This proposal has been marked as "stage 3" which means "recommended for implementation". However, it's still a work in progress and isn't a part of JavaScript yet, so keep in mind that any code that uses JavaScript decorator metadata may need to be updated as the feature continues to evolve. If/when that happens, I will update esbuild's implementation to match the specification. I will not be supporting old versions of the specification. * Fix bundled decorators in derived classes ([#3768](https://github.com/evanw/esbuild/issues/3768)) In certain cases, bundling code that uses decorators in a derived class with a class body that references its own class name could previously generate code that crashes at run-time due to an incorrect variable name. This problem has been fixed. Here is an example of code that was compiled incorrectly before this fix: ```js class Foo extends Object { @(x => x) foo() { return Foo } } console.log(new Foo().foo()) ``` * Fix `tsconfig.json` files inside symlinked directories ([#3767](https://github.com/evanw/esbuild/issues/3767)) This release fixes an issue with a scenario involving a `tsconfig.json` file that `extends` another file from within a symlinked directory that uses the `paths` feature. In that case, the implicit `baseURL` value should be based on the real path (i.e. after expanding all symbolic links) instead of the original path. This was already done for other files that esbuild resolves but was not yet done for `tsconfig.json` because it's special-cased (the regular path resolver can't be used because the information inside `tsconfig.json` is involved in path resolution). Note that this fix no longer applies if the `--preserve-symlinks` setting is enabled. ### v0.21.2 * Correct `this` in field and accessor decorators ([#3761](https://github.com/evanw/esbuild/issues/3761)) This release changes the value of `this` in initializers for class field and accessor decorators from the module-level `this` value to the appropriate `this` value for the decorated element (either the class or the instance). It was previously incorrect due to lack of test coverage. Here's an example of a decorator that doesn't work without this change: ```js const dec = () => function() { this.bar = true } class Foo { @dec static foo } console.log(Foo.bar) // Should be "true" ``` * Allow `es2023` as a target environment ([#3762](https://github.com/evanw/esbuild/issues/3762)) TypeScript recently [added `es2023`](https://github.com/microsoft/TypeScript/pull/58140) as a compilation target, so esbuild now supports this too. There is no difference between a target of `es2022` and `es2023` as far as esbuild is concerned since the 2023 edition of JavaScript doesn't introduce any new syntax features. ### v0.21.1 * Fix a regression with `--keep-names` ([#3756](https://github.com/evanw/esbuild/issues/3756)) The previous release introduced a regression with the `--keep-names` setting and object literals with `get`/`set` accessor methods, in which case the generated code contained syntax errors. This release fixes the regression: ```js // Original code x = { get y() {} } // Output from version 0.21.0 (with --keep-names) x = { get y: /* @__PURE__ */ __name(function() { }, "y") }; // Output from this version (with --keep-names) x = { get y() { } }; ``` ### v0.21.0 This release doesn't contain any deliberately-breaking changes. However, it contains a very complex new feature and while all of esbuild's tests pass, I would not be surprised if an important edge case turns out to be broken. So I'm releasing this as a breaking change release to avoid causing any trouble. As usual, make sure to test your code when you upgrade. * Implement the JavaScript decorators proposal ([#104](https://github.com/evanw/esbuild/issues/104)) With this release, esbuild now contains an implementation of the upcoming [JavaScript decorators proposal](https://github.com/tc39/proposal-decorators). This is the same feature that shipped in [TypeScript 5.0](https://devblogs.microsoft.com/typescript/announcing-typescript-5-0/#decorators) and has been highly-requested on esbuild's issue tracker. You can read more about them in that blog post and in this other (now slightly outdated) extensive blog post here: https://2ality.com/2022/10/javascript-decorators.html. Here's a quick example: ```js const log = (fn, context) => function() { console.log(`before ${context.name}`) const it = fn.apply(this, arguments) console.log(`after ${context.name}`) return it } class Foo { @log static foo() { console.log('in foo') } } // Logs "before foo", "in foo", "after foo" Foo.foo() ``` Note that this feature is different than the existing "TypeScript experimental decorators" feature that esbuild already implements. It uses similar syntax but behaves very differently, and the two are not compatible (although it's sometimes possible to write decorators that work with both). TypeScript experimental decorators will still be supported by esbuild going forward as they have been around for a long time, are very widely used, and let you do certain things that are not possible with JavaScript decorators (such as decorating function parameters). By default esbuild will parse and transform JavaScript decorators, but you can tell esbuild to parse and transform TypeScript experimental decorators instead by setting `"experimentalDecorators": true` in your `tsconfig.json` file. Probably at least half of the work for this feature went into creating a test suite that exercises many of the proposal's edge cases: https://github.com/evanw/decorator-tests. It has given me a reasonable level of confidence that esbuild's initial implementation is acceptable. However, I don't have access to a significant sample of real code that uses JavaScript decorators. If you're currently using JavaScript decorators in a real code base, please try out esbuild's implementation and let me know if anything seems off. **⚠️ WARNING ⚠️** This proposal has been in the works for a very long time (work began around 10 years ago in 2014) and it is finally getting close to becoming part of the JavaScript language. However, it's still a work in progress and isn't a part of JavaScript yet, so keep in mind that any code that uses JavaScript decorators may need to be updated as the feature continues to evolve. The decorators proposal is pretty close to its final form but it can and likely will undergo some small behavioral adjustments before it ends up becoming a part of the standard. If/when that happens, I will update esbuild's implementation to match the specification. I will not be supporting old versions of the specification. * Optimize the generated code for private methods Previously when lowering private methods for old browsers, esbuild would generate one `WeakSet` for each private method. This mirrors similar logic for generating one `WeakSet` for each private field. Using a separate `WeakMap` for private fields is necessary as their assignment can be observable: ```js let it class Bar { constructor() { it = this } } class Foo extends Bar { #x = 1 #y = null.foo static check() { console.log(#x in it, #y in it) } } try { new Foo } catch {} Foo.check() ``` This prints `true false` because this partially-initialized instance has `#x` but not `#y`. In other words, it's not true that all class instances will always have all of their private fields. However, the assignment of private methods to a class instance is not observable. In other words, it's true that all class instances will always have all of their private methods. This means esbuild can lower private methods into code where all methods share a single `WeakSet`, which is smaller, faster, and uses less memory. Other JavaScript processing tools such as the TypeScript compiler already make this optimization. Here's what this change looks like: ```js // Original code class Foo { #x() { return this.#x() } #y() { return this.#y() } #z() { return this.#z() } } // Old output (--supported:class-private-method=false) var _x, x_fn, _y, y_fn, _z, z_fn; class Foo { constructor() { __privateAdd(this, _x); __privateAdd(this, _y); __privateAdd(this, _z); } } _x = new WeakSet(); x_fn = function() { return __privateMethod(this, _x, x_fn).call(this); }; _y = new WeakSet(); y_fn = function() { return __privateMethod(this, _y, y_fn).call(this); }; _z = new WeakSet(); z_fn = function() { return __privateMethod(this, _z, z_fn).call(this); }; // New output (--supported:class-private-method=false) var _Foo_instances, x_fn, y_fn, z_fn; class Foo { constructor() { __privateAdd(this, _Foo_instances); } } _Foo_instances = new WeakSet(); x_fn = function() { return __privateMethod(this, _Foo_instances, x_fn).call(this); }; y_fn = function() { return __privateMethod(this, _Foo_instances, y_fn).call(this); }; z_fn = function() { return __privateMethod(this, _Foo_instances, z_fn).call(this); }; ``` * Fix an obscure bug with lowering class members with computed property keys When class members that use newer syntax features are transformed for older target environments, they sometimes need to be relocated. However, care must be taken to not reorder any side effects caused by computed property keys. For example, the following code must evaluate `a()` then `b()` then `c()`: ```js class Foo { [a()]() {} [b()]; static { c() } } ``` Previously esbuild did this by shifting the computed property key _forward_ to the next spot in the evaluation order. Classes evaluate all computed keys first and then all static class elements, so if the last computed key needs to be shifted, esbuild previously inserted a static block at start of the class body, ensuring it came before all other static class elements: ```js var _a; class Foo { constructor() { __publicField(this, _a); } static { _a = b(); } [a()]() { } static { c(); } } ``` However, this could cause esbuild to accidentally generate a syntax error if the computed property key contains code that isn't allowed in a static block, such as an `await` expression. With this release, esbuild fixes this problem by shifting the computed property key _backward_ to the previous spot in the evaluation order instead, which may push it into the `extends` clause or even before the class itself: ```js // Original code class Foo { [a()]() {} [await b()]; static { c() } } // Old output (with --supported:class-field=false) var _a; class Foo { constructor() { __publicField(this, _a); } static { _a = await b(); } [a()]() { } static { c(); } } // New output (with --supported:class-field=false) var _a, _b; class Foo { constructor() { __publicField(this, _a); } [(_b = a(), _a = await b(), _b)]() { } static { c(); } } ``` * Fix some `--keep-names` edge cases The [`NamedEvaluation` syntax-directed operation](https://tc39.es/ecma262/#sec-runtime-semantics-namedevaluation) in the JavaScript specification gives certain anonymous expressions a `name` property depending on where they are in the syntax tree. For example, the following initializers convey a `name` value: ```js var foo = function() {} var bar = class {} console.log(foo.name, bar.name) ``` When you enable esbuild's `--keep-names` setting, esbuild generates additional code to represent this `NamedEvaluation` operation so that the value of the `name` property persists even when the identifiers are renamed (e.g. due to minification). However, I recently learned that esbuild's implementation of `NamedEvaluation` is missing a few cases. Specifically esbuild was missing property definitions, class initializers, logical-assignment operators. These cases should now all be handled: ```js var obj = { foo: function() {} } class Foo0 { foo = function() {} } class Foo1 { static foo = function() {} } class Foo2 { accessor foo = function() {} } class Foo3 { static accessor foo = function() {} } foo ||= function() {} foo &&= function() {} foo ??= function() {} ``` ### v0.20.2 * Support TypeScript experimental decorators on `abstract` class fields ([#3684](https://github.com/evanw/esbuild/issues/3684)) With this release, you can now use TypeScript experimental decorators on `abstract` class fields. This was silently compiled incorrectly in esbuild 0.19.7 and below, and was an error from esbuild 0.19.8 to esbuild 0.20.1. Code such as the following should now work correctly: ```ts // Original code const log = (x: any, y: string) => console.log(y) abstract class Foo { @log abstract foo: string } new class extends Foo { foo = '' } // Old output (with --loader=ts --tsconfig-raw={\"compilerOptions\":{\"experimentalDecorators\":true}}) const log = (x, y) => console.log(y); class Foo { } new class extends Foo { foo = ""; }(); // New output (with --loader=ts --tsconfig-raw={\"compilerOptions\":{\"experimentalDecorators\":true}}) const log = (x, y) => console.log(y); class Foo { } __decorateClass([ log ], Foo.prototype, "foo", 2); new class extends Foo { foo = ""; }(); ``` * JSON loader now preserves `__proto__` properties ([#3700](https://github.com/evanw/esbuild/issues/3700)) Copying JSON source code into a JavaScript file will change its meaning if a JSON object contains the `__proto__` key. A literal `__proto__` property in a JavaScript object literal sets the prototype of the object instead of adding a property named `__proto__`, while a literal `__proto__` property in a JSON object literal just adds a property named `__proto__`. With this release, esbuild will now work around this problem by converting JSON to JavaScript with a computed property key in this case: ```js // Original code import data from 'data:application/json,{"__proto__":{"fail":true}}' if (Object.getPrototypeOf(data)?.fail) throw 'fail' // Old output (with --bundle) (() => { // <data:application/json,{"__proto__":{"fail":true}}> var json_proto_fail_true_default = { __proto__: { fail: true } }; // entry.js if (Object.getPrototypeOf(json_proto_fail_true_default)?.fail) throw "fail"; })(); // New output (with --bundle) (() => { // <data:application/json,{"__proto__":{"fail":true}}> var json_proto_fail_true_default = { ["__proto__"]: { fail: true } }; // example.mjs if (Object.getPrototypeOf(json_proto_fail_true_default)?.fail) throw "fail"; })(); ``` * Improve dead code removal of `switch` statements ([#3659](https://github.com/evanw/esbuild/issues/3659)) With this release, esbuild will now remove `switch` statements in branches when minifying if they are known to never be evaluated: ```js // Original code if (true) foo(); else switch (bar) { case 1: baz(); break } // Old output (with --minify) if(1)foo();else switch(bar){case 1:} // New output (with --minify) foo(); ``` * Empty enums should behave like an object literal ([#3657](https://github.com/evanw/esbuild/issues/3657)) TypeScript allows you to create an empty enum and add properties to it at run time. While people usually use an empty object literal for this instead of a TypeScript enum, esbuild's enum transform didn't anticipate this use case and generated `undefined` instead of `{}` for an empty enum. With this release, you can now use an empty enum to generate an empty object literal. ```ts // Original code enum Foo {} // Old output (with --loader=ts) var Foo = /* @__PURE__ */ ((Foo2) => { })(Foo || {}); // New output (with --loader=ts) var Foo = /* @__PURE__ */ ((Foo2) => { return Foo2; })(Foo || {}); ``` * Handle Yarn Plug'n'Play edge case with `tsconfig.json` ([#3698](https://github.com/evanw/esbuild/issues/3698)) Previously a `tsconfig.json` file that `extends` another file in a package with an `exports` map failed to work when Yarn's Plug'n'Play resolution was active. This edge case should work now starting with this release. * Work around issues with Deno 1.31+ ([#3682](https://github.com/evanw/esbuild/issues/3682)) Version 0.20.0 of esbuild changed how the esbuild child process is run in esbuild's API for Deno. Previously it used `Deno.run` but that API is being removed in favor of `Deno.Command`. As part of this change, esbuild is now calling the new `unref` function on esbuild's long-lived child process, which is supposed to allow Deno to exit when your code has finished running even though the child process is still around (previously you had to explicitly call esbuild's `stop()` function to terminate the child process for Deno to be able to exit). However, this introduced a problem for Deno's testing API which now fails some tests that use esbuild with `error: Promise resolution is still pending but the event loop has already resolved`. It's unclear to me why this is happening. The call to `unref` was recommended by someone on the Deno core team, and calling Node's equivalent `unref` API has been working fine for esbuild in Node for a long time. It could be that I'm using it incorrectly, or that there's some reference counting and/or garbage collection bug in Deno's internals, or that Deno's `unref` just works differently than Node's `unref`. In any case, it's not good for Deno tests that use esbuild to be failing. In this release, I am removing the call to `unref` to fix this issue. This means that you will now have to call esbuild's `stop()` function to allow Deno to exit, just like you did before esbuild version 0.20.0 when this regression was introduced. Note: This regression wasn't caught earlier because Deno doesn't seem to fail tests that have outstanding `setTimeout` calls, which esbuild's test harness was using to enforce a maximum test runtime. Adding a `setTimeout` was allowing esbuild's Deno tests to succeed. So this regression doesn't necessarily apply to all people using tests in Deno. --- ✨ This PR was created by Minori, your friendly dependency updater! 🌸
minori added 1 commit 2026-02-05 07:23:18 -08:00
deps: update esbuild to 0.27.2
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minori added 1 commit 2026-02-16 07:09:07 -08:00
deps: update esbuild to 0.27.3
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minori added 1 commit 2026-03-23 07:04:19 -07:00
deps: update esbuild to 0.27.4
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minori added 1 commit 2026-04-12 07:04:41 -07:00
deps: update esbuild to 0.27.5
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minori added 1 commit 2026-04-13 07:03:54 -07:00
deps: update esbuild to 0.28.0
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