0.19.7

• Add support for bundling code that uses import attributes (#3384)

  JavaScript is gaining new syntax for associating a map of string key-value pairs with individual ESM imports. The proposal is still a work in progress and is still undergoing significant changes before being finalized. However, the first iteration has already been shipping in Chromium-based browsers for a while, and the second iteration has landed in V8 and is now shipping in node, so it makes sense for esbuild to support it. Here are the two major iterations of this proposal (so far):

  1. Import assertions (deprecated, will not be standardized)

     • Uses the assert keyword
     • Does not affect module resolution
     • Causes an error if the assertion fails
     • Shipping in Chrome 91+ (and in esbuild 0.11.22+)

  2. Import attributes (currently set to become standardized)

     • Uses the with keyword
     • Affects module resolution
     • Unknown attributes cause an error
     • Shipping in node 21+

  You can already use esbuild to bundle code that uses import assertions (the first iteration). However, this feature is mostly useless for bundlers because import assertions are not allowed to affect module resolution. It's basically only useful as an annotation on external imports, which esbuild will then preserve in the output for use in a browser (which would otherwise refuse to load certain imports).

  With this release, esbuild now supports bundling code that uses import attributes (the second iteration). This is much more useful for bundlers because they are allowed to affect module resolution, which means the key-value pairs can be provided to plugins. Here's an example, which uses esbuild's built-in support for the upcoming JSON module standard:

  // On static imports
  import foo from './package.json' with { type: 'json' }
  console.log(foo)
  
  // On dynamic imports
  const bar = await import('./package.json', { with: { type: 'json' } })
  console.log(bar)
  

  One important consequence of the change in semantics between import assertions and import attributes is that two imports with identical paths but different import attributes are now considered to be different modules. This is because the import attributes are provided to the loader, which might then use those attributes during loading. For example, you could imagine an image loader that produces an image of a different size depending on the import attributes.

  Import attributes are now reported in the metafile and are now provided to on-load plugins as a map in the with property. For example, here's an esbuild plugin that turns all imports with a type import attribute equal to 'cheese' into a module that exports the cheese emoji:

  const cheesePlugin = {
    name: 'cheese',
    setup(build) {
      build.onLoad({ filter: /.*/ }, args => {
        if (args.with.type === 'cheese') return {
          contents: `export default "🧀"`,
        }
      })
    }
  }
  
  require('esbuild').build({
    bundle: true,
    write: false,
    stdin: {
      contents: `
        import foo from 'data:text/javascript,' with { type: 'cheese' }
        console.log(foo)
      `,
    },
    plugins: [cheesePlugin],
  }).then(result => {
    const code = new Function(result.outputFiles[0].text)
    code()
  })
  

  Warning: It's possible that the second iteration of this feature may change significantly again even though it's already shipping in real JavaScript VMs (since it has already happened once before). In that case, esbuild may end up adjusting its implementation to match the eventual standard behavior. So keep in mind that by using this, you are using an unstable upcoming JavaScript feature that may undergo breaking changes in the future.

• Adjust TypeScript experimental decorator behavior (#3230, #3326, #3394)

  With this release, esbuild will now allow TypeScript experimental decorators to access both static class properties and #private class names. For example:

  const check =
    <T,>(a: T, b: T): PropertyDecorator =>
      () => console.log(a === b)
  
  async function test() {
    class Foo {
      static #foo = 1
      static bar = 1 + Foo.#foo
      @check(Foo.#foo, 1) a: any
      @check(Foo.bar, await Promise.resolve(2)) b: any
    }
  }
  
  test().then(() => console.log('pass'))
  

  This will now print true true pass when compiled by esbuild. Previously esbuild evaluated TypeScript decorators outside of the class body, so it didn't allow decorators to access Foo or #foo. Now esbuild does something different, although it's hard to concisely explain exactly what esbuild is doing now (see the background section below for more information).

  Note that TypeScript's experimental decorator support is currently buggy: TypeScript's compiler passes this test if only the first @check is present or if only the second @check is present, but TypeScript's compiler fails this test if both checks are present together. I haven't changed esbuild to match TypeScript's behavior exactly here because I'm waiting for TypeScript to fix these bugs instead.

  Some background: TypeScript experimental decorators don't have consistent semantics regarding the context that the decorators are evaluated in. For example, TypeScript will let you use await within a decorator, which implies that the decorator runs outside the class body (since await isn't supported inside a class body), but TypeScript will also let you use #private names, which implies that the decorator runs inside the class body (since #private names are only supported inside a class body). The value of this in a decorator is also buggy (the run-time value of this changes if any decorator in the class uses a #private name but the type of this doesn't change, leading to the type checker no longer matching reality). These inconsistent semantics make it hard for esbuild to implement this feature as decorator evaluation happens in some superposition of both inside and outside the class body that is particular to the internal implementation details of the TypeScript compiler.

• Forbid --keep-names when targeting old browsers (#3477)

  The --keep-names setting needs to be able to assign to the name property on functions and classes. However, before ES6 this property was non-configurable, and attempting to assign to it would throw an error. So with this release, esbuild will no longer allow you to enable this setting while also targeting a really old browser.

0.19.6

• Fix a constant folding bug with bigint equality

  This release fixes a bug where esbuild incorrectly checked for bigint equality by checking the equality of the bigint literal text. This is correct if the bigint doesn't have a radix because bigint literals without a radix are always in canonical form (since leading zeros are not allowed). However, this is incorrect if the bigint has a radix (e.g. 0x123n) because the canonical form is not enforced when a radix is present.

  // Original code
  console.log(!!0n, !!1n, 123n === 123n)
  console.log(!!0x0n, !!0x1n, 123n === 0x7Bn)
  
  // Old output
  console.log(false, true, true);
  console.log(true, true, false);
  
  // New output
  console.log(false, true, true);
  console.log(!!0x0n, !!0x1n, 123n === 0x7Bn);
  

• Add some improvements to the JavaScript minifier

  This release adds more cases to the JavaScript minifier, including support for inlining String.fromCharCode and String.prototype.charCodeAt when possible:

  // Original code
  document.onkeydown = e => e.keyCode === 'A'.charCodeAt(0) && console.log(String.fromCharCode(55358, 56768))
  
  // Old output (with --minify)
  document.onkeydown=o=>o.keyCode==="A".charCodeAt(0)&&console.log(String.fromCharCode(55358,56768));
  
  // New output (with --minify)
  document.onkeydown=o=>o.keyCode===65&&console.log("🧀");
  

  In addition, immediately-invoked function expressions (IIFEs) that return a single expression are now inlined when minifying. This makes it possible to use IIFEs in combination with @__PURE__ annotations to annotate arbitrary expressions as side-effect free without the IIFE wrapper impacting code size. For example:

  // Original code
  const sideEffectFreeOffset = /* @__PURE__ */ (() => computeSomething())()
  use(sideEffectFreeOffset)
  
  // Old output (with --minify)
  const e=(()=>computeSomething())();use(e);
  
  // New output (with --minify)
  const e=computeSomething();use(e);
  

• Automatically prefix the mask-composite CSS property for WebKit (#3493)

  The mask-composite property will now be prefixed as -webkit-mask-composite for older WebKit-based browsers. In addition to prefixing the property name, handling older browsers also requires rewriting the values since WebKit uses non-standard names for the mask composite modes:

  /* Original code */
  div {
    mask-composite: add, subtract, intersect, exclude;
  }
  
  /* New output (with --target=chrome100) */
  div {
    -webkit-mask-composite:
      source-over,
      source-out,
      source-in,
      xor;
    mask-composite:
      add,
      subtract,
      intersect,
      exclude;
  }
  

• Avoid referencing this from JSX elements in derived class constructors (#3454)

  When you enable --jsx=automatic and --jsx-dev, the JSX transform is supposed to insert this as the last argument to the jsxDEV function. I'm not sure exactly why this is and I can't find any specification for it, but in any case this causes the generated code to crash when you use a JSX element in a derived class constructor before the call to super() as this is not allowed to be accessed at that point. For example

  // Original code
  class ChildComponent extends ParentComponent {
    constructor() {
      super(<div />)
    }
  }
  
  // Problematic output (with --loader=jsx --jsx=automatic --jsx-dev)
  import { jsxDEV } from "react/jsx-dev-runtime";
  class ChildComponent extends ParentComponent {
    constructor() {
      super(/* @__PURE__ */ jsxDEV("div", {}, void 0, false, {
        fileName: "<stdin>",
        lineNumber: 3,
        columnNumber: 15
      }, this)); // The reference to "this" crashes here
    }
  }
  

  The TypeScript compiler doesn't handle this at all while the Babel compiler just omits this for the entire constructor (even after the call to super()). There seems to be no specification so I can't be sure that this change doesn't break anything important. But given that Babel is pretty loose with this and TypeScript doesn't handle this at all, I'm guessing this value isn't too important. React's blog post seems to indicate that this value was intended to be used for a React-specific migration warning at some point, so it could even be that this value is irrelevant now. Anyway the crash in this case should now be fixed.

• Allow package subpath imports to map to node built-ins (#3485)

  You are now able to use a subpath import in your package to resolve to a node built-in module. For example, with a package.json file like this:

  {
    "type": "module",
    "imports": {
      "#stream": {
        "node": "stream",
        "default": "./stub.js"
      }
    }
  }
  

  You can now import from node's stream module like this:

  import * as stream from '#stream';
  console.log(Object.keys(stream));
  

  This will import from node's stream module when the platform is node and from ./stub.js otherwise.

• No longer throw an error when a Symbol is missing (#3453)

  Certain JavaScript syntax features use special properties on the global Symbol object. For example, the asynchronous iteration syntax uses Symbol.asyncIterator. Previously esbuild's generated code for older browsers required this symbol to be polyfilled. However, starting with this release esbuild will use Symbol.for() to construct these symbols if they are missing instead of throwing an error about a missing polyfill. This means your code no longer needs to include a polyfill for missing symbols as long as your code also uses Symbol.for() for missing symbols.

• Parse upcoming changes to TypeScript syntax (#3490, #3491)

  With this release, you can now use from as the name of a default type-only import in TypeScript code, as well as of as the name of an await using loop iteration variable:

  import type from from 'from'
  for (await using of of of) ;
  

  This matches similar changes in the TypeScript compiler (#56376 and #55555) which will start allowing this syntax in an upcoming version of TypeScript. Please never actually write code like this.

  The type-only import syntax change was contributed by @magic-akari.

0.19.5

• Fix a regression in 0.19.0 regarding paths in tsconfig.json (#3354)

  The fix in esbuild version 0.19.0 to process tsconfig.json aliases before the --packages=external setting unintentionally broke an edge case in esbuild's handling of certain tsconfig.json aliases where there are multiple files with the same name in different directories. This release adjusts esbuild's behavior for this edge case so that it passes while still processing aliases before --packages=external. Please read the linked issue for more details.

• Fix a CSS font property minification bug (#3452)

  This release fixes a bug where esbuild's CSS minifier didn't insert a space between the font size and the font family in the font CSS shorthand property in the edge case where the original source code didn't already have a space and the leading string token was shortened to an identifier:

  /* Original code */
  .foo { font: 16px"Menlo"; }
  
  /* Old output (with --minify) */
  .foo{font:16pxMenlo}
  
  /* New output (with --minify) */
  .foo{font:16px Menlo}
  

• Fix bundling CSS with asset names containing spaces (#3410)

  Assets referenced via CSS url() tokens may cause esbuild to generate invalid output when bundling if the file name contains spaces (e.g. url(image 2.png)). With this release, esbuild will now quote all bundled asset references in url() tokens to avoid this problem. This only affects assets loaded using the file and copy loaders.

• Fix invalid CSS url() tokens in @import rules (#3426)

  In the future, CSS url() tokens may contain additional stuff after the URL. This is irrelevant today as no CSS specification does this. But esbuild previously had a bug where using these tokens in an @import rule resulted in malformed output. This bug has been fixed.

• Fix browser + false + type: module in package.json (#3367)

  The browser field in package.json allows you to map a file to false to have it be treated as an empty file when bundling for the browser. However, if package.json contains "type": "module" then all .js files will be considered ESM, not CommonJS. Importing a named import from an empty CommonJS file gives you undefined, but importing a named export from an empty ESM file is a build error. This release changes esbuild's interpretation of these files mapped to false in this situation from ESM to CommonJS to avoid generating build errors for named imports.

• Fix a bug in top-level await error reporting (#3400)

  Using require() on a file that contains top-level await is not allowed because require() must return synchronously and top-level await makes that impossible. You will get a build error if you try to bundle code that does this with esbuild. This release fixes a bug in esbuild's error reporting code for complex cases of this situation involving multiple levels of imports to get to the module containing the top-level await.

• Update to Unicode 15.1.0

  The character tables that determine which characters form valid JavaScript identifiers have been updated from Unicode version 15.0.0 to the newly-released Unicode version 15.1.0. I'm not putting an example in the release notes because all of the new characters will likely just show up as little squares since fonts haven't been updated yet. But you can read https://www.unicode.org/versions/Unicode15.1.0/#Summary for more information about the changes.

  This upgrade was contributed by @JLHwung.

0.19.4

• Fix printing of JavaScript decorators in tricky cases (#3396)

  This release fixes some bugs where esbuild's pretty-printing of JavaScript decorators could incorrectly produced code with a syntax error. The problem happened because esbuild sometimes substitutes identifiers for other expressions in the pretty-printer itself, but the decision about whether to wrap the expression or not didn't account for this. Here are some examples:

  // Original code
  import { constant } from './constants.js'
  import { imported } from 'external'
  import { undef } from './empty.js'
  class Foo {
    @constant()
    @imported()
    @undef()
    foo
  }
  
  // Old output (with --bundle --format=cjs --packages=external --minify-syntax)
  var import_external = require("external");
  var Foo = class {
    @123()
    @(0, import_external.imported)()
    @(void 0)()
    foo;
  };
  
  // New output (with --bundle --format=cjs --packages=external --minify-syntax)
  var import_external = require("external");
  var Foo = class {
    @(123())
    @((0, import_external.imported)())
    @((void 0)())
    foo;
  };
  

• Allow pre-release versions to be passed to target (#3388)

  People want to be able to pass version numbers for unreleased versions of node (which have extra stuff after the version numbers) to esbuild's target setting and have esbuild do something reasonable with them. These version strings are of course not present in esbuild's internal feature compatibility table because an unreleased version has not been released yet (by definition). With this release, esbuild will now attempt to accept these version strings passed to target and do something reasonable with them.

0.19.3

• Fix list-style-type with the local-css loader (#3325)

  The local-css loader incorrectly treated all identifiers provided to list-style-type as a custom local identifier. That included identifiers such as none which have special meaning in CSS, and which should not be treated as custom local identifiers. This release fixes this bug:

  /* Original code */
  ul { list-style-type: none }
  
  /* Old output (with --loader=local-css) */
  ul {
    list-style-type: stdin_none;
  }
  
  /* New output (with --loader=local-css) */
  ul {
    list-style-type: none;
  }
  

  Note that this bug only affected code using the local-css loader. It did not affect code using the css loader.

• Avoid inserting temporary variables before use strict (#3322)

  This release fixes a bug where esbuild could incorrectly insert automatically-generated temporary variables before use strict directives:

  // Original code
  function foo() {
    'use strict'
    a.b?.c()
  }
  
  // Old output (with --target=es6)
  function foo() {
    var _a;
    "use strict";
    (_a = a.b) == null ? void 0 : _a.c();
  }
  
  // New output (with --target=es6)
  function foo() {
    "use strict";
    var _a;
    (_a = a.b) == null ? void 0 : _a.c();
  }
  

• Adjust TypeScript enum output to better approximate tsc (#3329)

  TypeScript enum values can be either number literals or string literals. Numbers create a bidirectional mapping between the name and the value but strings only create a unidirectional mapping from the name to the value. When the enum value is neither a number literal nor a string literal, TypeScript and esbuild both default to treating it as a number:

  // Original TypeScript code
  declare const foo: any
  enum Foo {
    NUMBER = 1,
    STRING = 'a',
    OTHER = foo,
  }
  
  // Compiled JavaScript code (from "tsc")
  var Foo;
  (function (Foo) {
    Foo[Foo["NUMBER"] = 1] = "NUMBER";
    Foo["STRING"] = "a";
    Foo[Foo["OTHER"] = foo] = "OTHER";
  })(Foo || (Foo = {}));
  

  However, TypeScript does constant folding slightly differently than esbuild. For example, it may consider template literals to be string literals in some cases:

  // Original TypeScript code
  declare const foo = 'foo'
  enum Foo {
    PRESENT = `${foo}`,
    MISSING = `${bar}`,
  }
  
  // Compiled JavaScript code (from "tsc")
  var Foo;
  (function (Foo) {
    Foo["PRESENT"] = "foo";
    Foo[Foo["MISSING"] = `${bar}`] = "MISSING";
  })(Foo || (Foo = {}));
  

  The template literal initializer for PRESENT is treated as a string while the template literal initializer for MISSING is treated as a number. Previously esbuild treated both of these cases as a number but starting with this release, esbuild will now treat both of these cases as a string. This doesn't exactly match the behavior of tsc but in the case where the behavior diverges tsc reports a compile error, so this seems like acceptible behavior for esbuild. Note that handling these cases completely correctly would require esbuild to parse type declarations (see the declare keyword), which esbuild deliberately doesn't do.

• Ignore case in CSS in more places (#3316)

  This release makes esbuild's CSS support more case-agnostic, which better matches how browsers work. For example:

  /* Original code */
  @KeyFrames Foo { From { OpaCity: 0 } To { OpaCity: 1 } }
  body { CoLoR: YeLLoW }
  
  /* Old output (with --minify) */
  @KeyFrames Foo{From {OpaCity: 0} To {OpaCity: 1}}body{CoLoR:YeLLoW}
  
  /* New output (with --minify) */
  @KeyFrames Foo{0%{OpaCity:0}To{OpaCity:1}}body{CoLoR:#ff0}
  

  Please never actually write code like this.

• Improve the error message for null entries in exports (#3377)

  Package authors can disable package export paths with the exports map in package.json. With this release, esbuild now has a clearer error message that points to the null token in package.json itself instead of to the surrounding context. Here is an example of the new error message:

  ✘ [ERROR] Could not resolve "msw/browser"
  
      lib/msw-config.ts:2:28:
        2 │ import { setupWorker } from 'msw/browser';
          ╵                             ~~~~~~~~~~~~~
  
    The path "./browser" cannot be imported from package "msw" because it was explicitly disabled by
    the package author here:
  
      node_modules/msw/package.json:17:14:
        17 │       "node": null,
           ╵               ~~~~
  
    You can mark the path "msw/browser" as external to exclude it from the bundle, which will remove
    this error and leave the unresolved path in the bundle.
  

• Parse and print the with keyword in import statements

  JavaScript was going to have a feature called "import assertions" that adds an assert keyword to import statements. It looked like this:

  import stuff from './stuff.json' assert { type: 'json' }
  

  The feature provided a way to assert that the imported file is of a certain type (but was not allowed to affect how the import is interpreted, even though that's how everyone expected it to behave). The feature was fully specified and then actually implemented and shipped in Chrome before the people behind the feature realized that they should allow it to affect how the import is interpreted after all. So import assertions are no longer going to be added to the language.

  Instead, the current proposal is to add a feature called "import attributes" instead that adds a with keyword to import statements. It looks like this:

  import stuff from './stuff.json' with { type: 'json' }
  

  This feature provides a way to affect how the import is interpreted. With this release, esbuild now has preliminary support for parsing and printing this new with keyword. The with keyword is not yet interpreted by esbuild, however, so bundling code with it will generate a build error. All this release does is allow you to use esbuild to process code containing it (such as removing types from TypeScript code). Note that this syntax is not yet a part of JavaScript and may be removed or altered in the future if the specification changes (which it already has once, as described above). If that happens, esbuild reserves the right to remove or alter its support for this syntax too.

0.19.2

• Update how CSS nesting is parsed again

  CSS nesting syntax has been changed again, and esbuild has been updated to match. Type selectors may now be used with CSS nesting:

  .foo {
    div {
      color: red;
    }
  }
  

  Previously this was disallowed in the CSS specification because it's ambiguous whether an identifier is a declaration or a nested rule starting with a type selector without requiring unbounded lookahead in the parser. It has now been allowed because the CSS working group has decided that requiring unbounded lookahead is acceptable after all.

  Note that this change means esbuild no longer considers any existing browser to support CSS nesting since none of the existing browsers support this new syntax. CSS nesting will now always be transformed when targeting a browser. This situation will change in the future as browsers add support for this new syntax.

• Fix a scope-related bug with --drop-labels= (#3311)

  The recently-released --drop-labels= feature previously had a bug where esbuild's internal scope stack wasn't being restored properly when a statement with a label was dropped. This could manifest as a tree-shaking issue, although it's possible that this could have also been causing other subtle problems too. The bug has been fixed in this release.

• Make renamed CSS names unique across entry points (#3295)

  Previously esbuild's generated names for local names in CSS were only unique within a given entry point (or across all entry points when code splitting was enabled). That meant that building multiple entry points with esbuild could result in local names being renamed to the same identifier even when those entry points were built simultaneously within a single esbuild API call. This problem was especially likely to happen with minification enabled. With this release, esbuild will now avoid renaming local names from two separate entry points to the same name if those entry points were built with a single esbuild API call, even when code splitting is disabled.

• Fix CSS ordering bug with @layer before @import

  CSS lets you put @layer rules before @import rules to define the order of layers in a stylesheet. Previously esbuild's CSS bundler incorrectly ordered these after the imported files because before the introduction of cascade layers to CSS, imported files could be bundled by removing the @import rules and then joining files together in the right order. But with @layer, CSS files may now need to be split apart into multiple pieces in the bundle. For example:

  /* Original code */
  @layer start;
  @import "data:text/css,@layer inner.start;";
  @import "data:text/css,@layer inner.end;";
  @layer end;
  
  /* Old output (with --bundle) */
  @layer inner.start;
  @layer inner.end;
  @layer start;
  @layer end;
  
  /* New output (with --bundle) */
  @layer start;
  @layer inner.start;
  @layer inner.end;
  @layer end;
  

• Unwrap nested duplicate @media rules (#3226)

  With this release, esbuild's CSS minifier will now automatically unwrap duplicate nested @media rules:

  /* Original code */
  @media (min-width: 1024px) {
    .foo { color: red }
    @media (min-width: 1024px) {
      .bar { color: blue }
    }
  }
  
  /* Old output (with --minify) */
  @media (min-width: 1024px){.foo{color:red}@media (min-width: 1024px){.bar{color:#00f}}}
  
  /* New output (with --minify) */
  @media (min-width: 1024px){.foo{color:red}.bar{color:#00f}}
  

  These rules are unlikely to be authored manually but may result from using frameworks such as Tailwind to generate CSS.

0.19.1

• Fix a regression with baseURL in tsconfig.json (#3307)

  The previous release moved tsconfig.json path resolution before --packages=external checks to allow the paths field in tsconfig.json to avoid a package being marked as external. However, that reordering accidentally broke the behavior of the baseURL field from tsconfig.json. This release moves these path resolution rules around again in an attempt to allow both of these cases to work.

• Parse TypeScript type arguments for JavaScript decorators (#3308)

  When parsing JavaScript decorators in TypeScript (i.e. with experimentalDecorators disabled), esbuild previously didn't parse type arguments. Type arguments will now be parsed starting with this release. For example:

  @foo<number>
  @bar<number, string>()
  class Foo {}
  

• Fix glob patterns matching extra stuff at the end (#3306)

  Previously glob patterns such as ./*.js would incorrectly behave like ./*.js* during path matching (also matching .js.map files, for example). This was never intentional behavior, and has now been fixed.

• Change the permissions of esbuild's generated output files (#3285)

  This release changes the permissions of the output files that esbuild generates to align with the default behavior of node's fs.writeFileSync function. Since most tools written in JavaScript use fs.writeFileSync, this should make esbuild more consistent with how other JavaScript build tools behave.

  The full Unix-y details: Unix permissions use three-digit octal notation where the three digits mean "user, group, other" in that order. Within a digit, 4 means "read" and 2 means "write" and 1 means "execute". So 6 == 4 + 2 == read + write. Previously esbuild uses 0644 permissions (the leading 0 means octal notation) but the permissions for fs.writeFileSync defaults to 0666, so esbuild will now use 0666 permissions. This does not necessarily mean that the files esbuild generates will end up having 0666 permissions, however, as there is another Unix feature called "umask" where the operating system masks out some of these bits. If your umask is set to 0022 then the generated files will have 0644 permissions, and if your umask is set to 0002 then the generated files will have 0664 permissions.

• Fix a subtle CSS ordering issue with @import and @layer

  With this release, esbuild may now introduce additional @layer rules when bundling CSS to better preserve the layer ordering of the input code. Here's an example of an edge case where this matters:

  /* entry.css */
  @import "a.css";
  @import "b.css";
  @import "a.css";
  

  /* a.css */
  @layer a {
    body {
      background: red;
    }
  }
  

  /* b.css */
  @layer b {
    body {
      background: green;
    }
  }
  

  This CSS should set the body background to green, which is what happens in the browser. Previously esbuild generated the following output which incorrectly sets the body background to red:

  /* b.css */
  @layer b {
    body {
      background: green;
    }
  }
  
  /* a.css */
  @layer a {
    body {
      background: red;
    }
  }
  

  This difference in behavior is because the browser evaluates a.css + b.css + a.css (in CSS, each @import is replaced with a copy of the imported file) while esbuild was only writing out b.css + a.css. The first copy of a.css wasn't being written out by esbuild for two reasons: 1) bundlers care about code size and try to avoid emitting duplicate CSS and 2) when there are multiple copies of a CSS file, normally only the last copy matters since the last declaration with equal specificity wins in CSS.

  However, @layer was recently added to CSS and for @layer the first copy matters because layers are ordered using their first location in source code order. This introduction of @layer means esbuild needs to change its bundling algorithm. An easy solution would be for esbuild to write out a.css twice, but that would be inefficient. So what I'm going to try to have esbuild do with this release is to write out an abbreviated form of the first copy of a CSS file that only includes the @layer information, and then still only write out the full CSS file once for the last copy. So esbuild's output for this edge case now looks like this:

  /* a.css */
  @layer a;
  
  /* b.css */
  @layer b {
    body {
      background: green;
    }
  }
  
  /* a.css */
  @layer a {
    body {
      background: red;
    }
  }
  

  The behavior of the bundled CSS now matches the behavior of the unbundled CSS. You may be wondering why esbuild doesn't just write out a.css first followed by b.css. That would work in this case but it doesn't work in general because for any rules outside of a @layer rule, the last copy should still win instead of the first copy.

• Fix a bug with esbuild's TypeScript type definitions (#3299)

  This release fixes a copy/paste error with the TypeScript type definitions for esbuild's JS API:

   export interface TsconfigRaw {
     compilerOptions?: {
  -    baseUrl?: boolean
  +    baseUrl?: string
       ...
     }
   }
  

  This fix was contributed by @privatenumber.

0.19.0

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 ^0.18.0 or ~0.18.0. See npm's documentation about semver for more information.

• Handle import paths containing wildcards (#56, #700, #875, #976, #2221, #2515)

  This release introduces wildcards in import paths in two places:

  • Entry points

    You can now pass a string containing glob-style wildcards such as ./src/*.ts as an entry point and esbuild will search the file system for files that match the pattern. This can be used to easily pass esbuild all files with a certain extension on the command line in a cross-platform way. Previously you had to rely on the shell to perform glob expansion, but that is obviously shell-dependent and didn't work at all on Windows. Note that to use this feature on the command line you will have to quote the pattern so it's passed verbatim to esbuild without any expansion by the shell. Here's an example:

    esbuild --minify "./src/*.ts" --outdir=out
    

    Specifically the * character will match any character except for the / character, and the /**/ character sequence will match a path separator followed by zero or more path elements. Other wildcard operators found in glob patterns such as ? and [...] are not supported.

  • Run-time import paths

    Import paths that are evaluated at run-time can now be bundled in certain limited situations. The import path expression must be a form of string concatenation and must start with either ./ or ../. Each non-string expression in the string concatenation chain becomes a wildcard. The * wildcard is chosen unless the previous character is a /, in which case the /**/* character sequence is used. Some examples:

    // These two forms are equivalent
    const json1 = await import('./data/' + kind + '.json')
    const json2 = await import(`./data/${kind}.json`)
    

    This feature works with require(...) and import(...) because these can all accept run-time expressions. It does not work with import and export statements because these cannot accept run-time expressions. If you want to prevent esbuild from trying to bundle these imports, you should move the string concatenation expression outside of the require(...) or import(...). For example:

    // This will be bundled
    const json1 = await import('./data/' + kind + '.json')
    
    // This will not be bundled
    const path = './data/' + kind + '.json'
    const json2 = await import(path)
    

    Note that using this feature means esbuild will potentially do a lot of file system I/O to find all possible files that might match the pattern. This is by design, and is not a bug. If this is a concern, I recommend either avoiding the /**/ pattern (e.g. by not putting a / before a wildcard) or using this feature only in directory subtrees which do not have many files that don't match the pattern (e.g. making a subdirectory for your JSON files and explicitly including that subdirectory in the pattern).

• Path aliases in tsconfig.json no longer count as packages (#2792, #3003, #3160, #3238)

  Setting --packages=external tells esbuild to make all import paths external when they look like a package path. For example, an import of ./foo/bar is not a package path and won't be external while an import of foo/bar is a package path and will be external. However, the paths field in tsconfig.json allows you to create import paths that look like package paths but that do not resolve to packages. People do not want these paths to count as package paths. So with this release, the behavior of --packages=external has been changed to happen after the tsconfig.json path remapping step.

• Use the local-css loader for .module.css files by default (#20)

  With this release the css loader is still used for .css files except that .module.css files now use the local-css loader. This is a common convention in the web development community. If you need .module.css files to use the css loader instead, then you can override this behavior with --loader:.module.css=css.

0.18.20

• Support advanced CSS @import rules (#953, #3137)

  CSS @import statements have been extended to allow additional trailing tokens after the import path. These tokens sort of make the imported file behave as if it were wrapped in a @layer, @supports, and/or @media rule. Here are some examples:

  @import url(foo.css);
  @import url(foo.css) layer;
  @import url(foo.css) layer(bar);
  @import url(foo.css) layer(bar) supports(display: flex);
  @import url(foo.css) layer(bar) supports(display: flex) print;
  @import url(foo.css) layer(bar) print;
  @import url(foo.css) supports(display: flex);
  @import url(foo.css) supports(display: flex) print;
  @import url(foo.css) print;
  

  You can read more about this advanced syntax here. With this release, esbuild will now bundle @import rules with these trailing tokens and will wrap the imported files in the corresponding rules. Note that this now means a given imported file can potentially appear in multiple places in the bundle. However, esbuild will still only load it once (e.g. on-load plugins will only run once per file, not once per import).

0.18.19

• Implement composes from CSS modules (#20)

  This release implements the composes annotation from the CSS modules specification. It provides a way for class selectors to reference other class selectors (assuming you are using the local-css loader). And with the from syntax, this can even work with local names across CSS files. For example:

  // app.js
  import { submit } from './style.css'
  const div = document.createElement('div')
  div.className = submit
  document.body.appendChild(div)
  

  /* style.css */
  .button {
    composes: pulse from "anim.css";
    display: inline-block;
  }
  .submit {
    composes: button;
    font-weight: bold;
  }
  

  /* anim.css */
  @keyframes pulse {
    from, to { opacity: 1 }
    50% { opacity: 0.5 }
  }
  .pulse {
    animation: 2s ease-in-out infinite pulse;
  }
  

  Bundling this with esbuild using --bundle --outdir=dist --loader:.css=local-css now gives the following:

  (() => {
    // style.css
    var submit = "anim_pulse style_button style_submit";
  
    // app.js
    var div = document.createElement("div");
    div.className = submit;
    document.body.appendChild(div);
  })();
  

  /* anim.css */
  @keyframes anim_pulse {
    from, to {
      opacity: 1;
    }
    50% {
      opacity: 0.5;
    }
  }
  .anim_pulse {
    animation: 2s ease-in-out infinite anim_pulse;
  }
  
  /* style.css */
  .style_button {
    display: inline-block;
  }
  .style_submit {
    font-weight: bold;
  }
  

  Import paths in the composes: ... from syntax are resolved using the new composes-from import kind, which can be intercepted by plugins during import path resolution when bundling is enabled.

  Note that the order in which composed CSS classes from separate files appear in the bundled output file is deliberately undefined by design (see the specification for details). You are not supposed to declare the same CSS property in two separate class selectors and then compose them together. You are only supposed to compose CSS class selectors that declare non-overlapping CSS properties.

  Issue #20 (the issue tracking CSS modules) is esbuild's most-upvoted issue! With this change, I now consider esbuild's implementation of CSS modules to be complete. There are still improvements to make and there may also be bugs with the current implementation, but these can be tracked in separate issues.

• Fix non-determinism with tsconfig.json and symlinks (#3284)

  This release fixes an issue that could cause esbuild to sometimes emit incorrect build output in cases where a file under the effect of tsconfig.json is inconsistently referenced through a symlink. It can happen when using npm link to create a symlink within node_modules to an unpublished package. The build result was non-deterministic because esbuild runs module resolution in parallel and the result of the tsconfig.json lookup depended on whether the import through the symlink or not through the symlink was resolved first. This problem was fixed by moving the realpath operation before the tsconfig.json lookup.

• Add a hash property to output files (#3084, #3293)

  As a convenience, every output file in esbuild's API now includes a hash property that is a hash of the contents field. This is the hash that's used internally by esbuild to detect changes between builds for esbuild's live-reload feature. You may also use it to detect changes between your own builds if its properties are sufficient for your use case.

  This feature has been added directly to output file objects since it's just a hash of the contents field, so it makes conceptual sense to store it in the same location. Another benefit of putting it there instead of including it as a part of the watch mode API is that it can be used without watch mode enabled. You can use it to compare the output of two independent builds that were done at different times.

  The hash algorithm (currently XXH64) is implementation-dependent and may be changed at any time in between esbuild versions. If you don't like esbuild's choice of hash algorithm then you are welcome to hash the contents yourself instead. As with any hash algorithm, note that while two different hashes mean that the contents are different, two equal hashes do not necessarily mean that the contents are equal. You may still want to compare the contents in addition to the hashes to detect with certainty when output files have been changed.

• Avoid generating duplicate prefixed declarations in CSS (#3292)

  There was a request for esbuild's CSS prefixer to avoid generating a prefixed declaration if a declaration by that name is already present in the same rule block. So with this release, esbuild will now avoid doing this:

  /* Original code */
  body {
    backdrop-filter: blur(30px);
    -webkit-backdrop-filter: blur(45px);
  }
  
  /* Old output (with --target=safari12) */
  body {
    -webkit-backdrop-filter: blur(30px);
    backdrop-filter: blur(30px);
    -webkit-backdrop-filter: blur(45px);
  }
  
  /* New output (with --target=safari12) */
  body {
    backdrop-filter: blur(30px);
    -webkit-backdrop-filter: blur(45px);
  }
  

  This can result in a visual difference in certain cases (for example if the browser understands blur(30px) but not blur(45px), it will be able to fall back to blur(30px)). But this change means esbuild now matches the behavior of Autoprefixer which is probably a good representation of how people expect this feature to work.