v0.18.6

• Fix tree-shaking of classes with decorators (#3164)

  This release fixes a bug where esbuild incorrectly allowed tree-shaking on classes with decorators. Each decorator is a function call, so classes with decorators must never be tree-shaken. This bug was a regression that was unintentionally introduced in version 0.18.2 by the change that enabled tree-shaking of lowered private fields. Previously decorators were always lowered, and esbuild always considered the automatically-generated decorator code to be a side effect. But this is no longer the case now that esbuild analyzes side effects using the AST before lowering takes place. This bug was fixed by considering any decorator a side effect.

• Fix a minification bug involving function expressions (#3125)

  When minification is enabled, esbuild does limited inlining of const symbols at the top of a scope. This release fixes a bug where inlineable symbols were incorrectly removed assuming that they were inlined. They may not be inlined in cases where they were referenced by earlier constants in the body of a function expression. The declarations involved in these edge cases are now kept instead of being removed:

  // Original code
  {
    const fn = () => foo
    const foo = 123
    console.log(fn)
  }
  
  // Old output (with --minify-syntax)
  console.log((() => foo)());
  
  // New output (with --minify-syntax)
  {
    const fn = () => foo, foo = 123;
    console.log(fn);
  }

v0.18.5

• Implement auto accessors (#3009)

  This release implements the new auto-accessor syntax from the upcoming JavaScript decorators proposal. The auto-accessor syntax looks like this:

  class Foo {
    accessor foo;
    static accessor bar;
  }
  new Foo().foo = Foo.bar;

  This syntax is not yet a part of JavaScript but it was added to TypeScript in version 4.9. More information about this feature can be found in microsoft/TypeScript#49705. Auto-accessors will be transformed if the target is set to something other than esnext:

  // Output (with --target=esnext)
  class Foo {
    accessor foo;
    static accessor bar;
  }
  new Foo().foo = Foo.bar;
  
  // Output (with --target=es2022)
  class Foo {
    #foo;
    get foo() {
      return this.#foo;
    }
    set foo(_) {
      this.#foo = _;
    }
    static #bar;
    static get bar() {
      return this.#bar;
    }
    static set bar(_) {
      this.#bar = _;
    }
  }
  new Foo().foo = Foo.bar;
  
  // Output (with --target=es2021)
  var _foo, _bar;
  class Foo {
    constructor() {
      __privateAdd(this, _foo, void 0);
    }
    get foo() {
      return __privateGet(this, _foo);
    }
    set foo(_) {
      __privateSet(this, _foo, _);
    }
    static get bar() {
      return __privateGet(this, _bar);
    }
    static set bar(_) {
      __privateSet(this, _bar, _);
    }
  }
  _foo = new WeakMap();
  _bar = new WeakMap();
  __privateAdd(Foo, _bar, void 0);
  new Foo().foo = Foo.bar;

  You can also now use auto-accessors with esbuild's TypeScript experimental decorator transformation, which should behave the same as decorating the underlying getter/setter pair.

  Please keep in mind that this syntax is not yet part of JavaScript. This release enables auto-accessors in .js files with the expectation that it will be a part of JavaScript soon. However, esbuild may change or remove this feature in the future if JavaScript ends up changing or removing this feature. Use this feature with caution for now.

• Pass through JavaScript decorators (#104)

  In this release, esbuild now parses decorators from the upcoming JavaScript decorators proposal and passes them through to the output unmodified (as long as the language target is set to esnext). Transforming JavaScript decorators to environments that don't support them has not been implemented yet. The only decorator transform that esbuild currently implements is still the TypeScript experimental decorator transform, which only works in .ts files and which requires "experimentalDecorators": true in your tsconfig.json file.

• Static fields with assign semantics now use static blocks if possible

  Setting useDefineForClassFields to false in TypeScript requires rewriting class fields to assignment statements. Previously this was done by removing the field from the class body and adding an assignment statement after the class declaration. However, this also caused any private fields to also be lowered by necessity (in case a field initializer uses a private symbol, either directly or indirectly). This release changes this transform to use an inline static block if it's supported, which avoids needing to lower private fields in this scenario:

  // Original code
  class Test {
    static #foo = 123
    static bar = this.#foo
  }
  
  // Old output (with useDefineForClassFields=false)
  var _foo;
  const _Test = class _Test {
  };
  _foo = new WeakMap();
  __privateAdd(_Test, _foo, 123);
  _Test.bar = __privateGet(_Test, _foo);
  let Test = _Test;
  
  // New output (with useDefineForClassFields=false)
  class Test {
    static #foo = 123;
    static {
      this.bar = this.#foo;
    }
  }

• Fix TypeScript experimental decorators combined with --mangle-props (#3177)

  Previously using TypeScript experimental decorators combined with the --mangle-props setting could result in a crash, as the experimental decorator transform was not expecting a mangled property as a class member. This release fixes the crash so you can now combine both of these features together safely.

v0.18.4

• Bundling no longer unnecessarily transforms class syntax (#1360, #1328, #1524, #2416)

  When bundling, esbuild automatically converts top-level class statements to class expressions. Previously this conversion had the unfortunate side-effect of also transforming certain other class-related syntax features to avoid correctness issues when the references to the class name within the class body. This conversion has been reworked to avoid doing this:

  // Original code
  export class Foo {
    static foo = () => Foo
  }
  
  // Old output (with --bundle)
  var _Foo = class {
  };
  var Foo = _Foo;
  __publicField(Foo, "foo", () => _Foo);
  
  // New output (with --bundle)
  var Foo = class _Foo {
    static foo = () => _Foo;
  };

  This conversion process is very complicated and has many edge cases (including interactions with static fields, static blocks, private class properties, and TypeScript experimental decorators). It should already be pretty robust but a change like this may introduce new unintentional behavior. Please report any issues with this upgrade on the esbuild bug tracker.

  You may be wondering why esbuild needs to do this at all. One reason to do this is that esbuild's bundler sometimes needs to lazily-evaluate a module. For example, a module may end up being both the target of a dynamic import() call and a static import statement. Lazy module evaluation is done by wrapping the top-level module code in a closure. To avoid a performance hit for static import statements, esbuild stores top-level exported symbols outside of the closure and references them directly instead of indirectly.

  Another reason to do this is that multiple JavaScript VMs have had and continue to have performance issues with TDZ (i.e. "temporal dead zone") checks. These checks validate that a let, or const, or class symbol isn't used before it's initialized. Here are two issues with well-known VMs:

  • V8: https://bugs.chromium.org/p/v8/issues/detail?id=13723 (10% slowdown)
  • JavaScriptCore: https://bugs.webkit.org/show_bug.cgi?id=199866 (1,000% slowdown!)

  JavaScriptCore had a severe performance issue as their TDZ implementation had time complexity that was quadratic in the number of variables needing TDZ checks in the same scope (with the top-level scope typically being the worst offender). V8 has ongoing issues with TDZ checks being present throughout the code their JIT generates even when they have already been checked earlier in the same function or when the function in question has already been run (so the checks have already happened).

  Due to esbuild's parallel architecture, esbuild both a) needs to convert class statements into class expressions during parsing and b) doesn't yet know whether this module will need to be lazily-evaluated or not in the parser. So esbuild always does this conversion during bundling in case it's needed for correctness (and also to avoid potentially catastrophic performance issues due to bundling creating a large scope with many TDZ variables).

• Enforce TDZ errors in computed class property keys (#2045)

  JavaScript allows class property keys to be generated at run-time using code, like this:

  class Foo {
    static foo = 'foo'
    static [Foo.foo + '2'] = 2
  }

  Previously esbuild treated references to the containing class name within computed property keys as a reference to the partially-initialized class object. That meant code that attempted to reference properties of the class object (such as the code above) would get back undefined instead of throwing an error.

  This release rewrites references to the containing class name within computed property keys into code that always throws an error at run-time, which is how this JavaScript code is supposed to work. Code that does this will now also generate a warning. You should never write code like this, but it now should be more obvious when incorrect code like this is written.

• Fix an issue with experimental decorators and static fields (#2629)

  This release also fixes a bug regarding TypeScript experimental decorators and static class fields which reference the enclosing class name in their initializer. This affected top-level classes when bundling was enabled. Previously code that does this could crash because the class name wasn't initialized yet. This case should now be handled correctly:

  // Original code
  class Foo {
    @someDecorator
    static foo = 'foo'
    static bar = Foo.foo.length
  }
  
  // Old output
  const _Foo = class {
    static foo = "foo";
    static bar = _Foo.foo.length;
  };
  let Foo = _Foo;
  __decorateClass([
    someDecorator
  ], Foo, "foo", 2);
  
  // New output
  const _Foo = class _Foo {
    static foo = "foo";
    static bar = _Foo.foo.length;
  };
  __decorateClass([
    someDecorator
  ], _Foo, "foo", 2);
  let Foo = _Foo;

• Fix a minification regression with negative numeric properties (#3169)

  Version 0.18.0 introduced a regression where computed properties with negative numbers were incorrectly shortened into a non-computed property when minification was enabled. This regression has been fixed:

  // Original code
  x = {
    [1]: 1,
    [-1]: -1,
    [NaN]: NaN,
    [Infinity]: Infinity,
    [-Infinity]: -Infinity,
  }
  
  // Old output (with --minify)
  x={1:1,-1:-1,NaN:NaN,1/0:1/0,-1/0:-1/0};
  
  // New output (with --minify)
  x={1:1,[-1]:-1,NaN:NaN,[1/0]:1/0,[-1/0]:-1/0};

v0.18.3

• Fix a panic due to empty static class blocks (#3161)

  This release fixes a bug where an internal invariant that was introduced in the previous release was sometimes violated, which then caused a panic. It happened when bundling code containing an empty static class block with both minification and bundling enabled.

v0.18.2

• Lower static blocks when static fields are lowered (#2800, #2950, #3025)

  This release fixes a bug where esbuild incorrectly did not lower static class blocks when static class fields needed to be lowered. For example, the following code should print 1 2 3 but previously printed 2 1 3 instead due to this bug:

  // Original code
  class Foo {
    static x = console.log(1)
    static { console.log(2) }
    static y = console.log(3)
  }
  
  // Old output (with --supported:class-static-field=false)
  class Foo {
    static {
      console.log(2);
    }
  }
  __publicField(Foo, "x", console.log(1));
  __publicField(Foo, "y", console.log(3));
  
  // New output (with --supported:class-static-field=false)
  class Foo {
  }
  __publicField(Foo, "x", console.log(1));
  console.log(2);
  __publicField(Foo, "y", console.log(3));

• Use static blocks to implement --keep-names on classes (#2389)

  This change fixes a bug where the name property could previously be incorrect within a class static context when using --keep-names. The problem was that the name property was being initialized after static blocks were run instead of before. This has been fixed by moving the name property initializer into a static block at the top of the class body:

  // Original code
  if (typeof Foo === 'undefined') {
    let Foo = class {
      static test = this.name
    }
    console.log(Foo.test)
  }
  
  // Old output (with --keep-names)
  if (typeof Foo === "undefined") {
    let Foo2 = /* @__PURE__ */ __name(class {
      static test = this.name;
    }, "Foo");
    console.log(Foo2.test);
  }
  
  // New output (with --keep-names)
  if (typeof Foo === "undefined") {
    let Foo2 = class {
      static {
        __name(this, "Foo");
      }
      static test = this.name;
    };
    console.log(Foo2.test);
  }

  This change was somewhat involved, especially regarding what esbuild considers to be side-effect free. Some unused classes that weren't removed by tree shaking in previous versions of esbuild may now be tree-shaken. One example is classes with static private fields that are transformed by esbuild into code that doesn't use JavaScript's private field syntax. Previously esbuild's tree shaking analysis ran on the class after syntax lowering, but with this release it will run on the class before syntax lowering, meaning it should no longer be confused by class mutations resulting from automatically-generated syntax lowering code.

v0.18.1

• Fill in null entries in input source maps (#3144)

  If esbuild bundles input files with source maps and those source maps contain a sourcesContent array with null entries, esbuild previously copied those null entries over to the output source map. With this release, esbuild will now attempt to fill in those null entries by looking for a file on the file system with the corresponding name from the sources array. This matches esbuild's existing behavior that automatically generates the sourcesContent array from the file system if the entire sourcesContent array is missing.

• Support /* @__KEY__ */ comments for mangling property names (#2574)

  Property mangling is an advanced feature that enables esbuild to minify certain property names, even though it's not possible to automatically determine that it's safe to do so. The safe property names are configured via regular expression such as --mangle-props=_$ (mangle all properties ending in _).

  Sometimes it's desirable to also minify strings containing property names, even though it's not possible to automatically determine which strings are property names. This release makes it possible to do this by annotating those strings with /* @__KEY__ */. This is a convention that Terser added earlier this year, and which esbuild is now following too: terser/terser#1365. Using it looks like this:

  // Original code
  console.log(
    [obj.mangle_, obj.keep],
    [obj.get('mangle_'), obj.get('keep')],
    [obj.get(/* @__KEY__ */ 'mangle_'), obj.get(/* @__KEY__ */ 'keep')],
  )
  
  // Old output (with --mangle-props=_$)
  console.log(
    [obj.a, obj.keep],
    [obj.get("mangle_"), obj.get("keep")],
    [obj.get(/* @__KEY__ */ "mangle_"), obj.get(/* @__KEY__ */ "keep")]
  );
  
  // New output (with --mangle-props=_$)
  console.log(
    [obj.a, obj.keep],
    [obj.get("mangle_"), obj.get("keep")],
    [obj.get(/* @__KEY__ */ "a"), obj.get(/* @__KEY__ */ "keep")]
  );

• Support /* @__NO_SIDE_EFFECTS__ */ comments for functions (#3149)

  Rollup has recently added support for /* @__NO_SIDE_EFFECTS__ */ annotations before functions to indicate that calls to these functions can be removed if the result is unused (i.e. the calls can be assumed to have no side effects). This release adds basic support for these to esbuild as well, which means esbuild will now parse these comments in input files and preserve them in output files. This should help people that use esbuild in combination with Rollup.

  Note that this doesn't necessarily mean esbuild will treat these calls as having no side effects, as esbuild's parallel architecture currently isn't set up to enable this type of cross-file tree-shaking information (tree-shaking decisions regarding a function call are currently local to the file they appear in). If you want esbuild to consider a function call to have no side effects, make sure you continue to annotate the function call with /* @__PURE__ */ (which is the previously-established convention for communicating this).

v0.18.0

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 ^0.17.0 or ~0.17.0. See npm's documentation about semver for more information.

The breaking changes in this release mainly focus on fixing some long-standing issues with esbuild's handling of tsconfig.json files. Here are all the changes in this release, in detail:

• Add a way to try esbuild online (#797)

  There is now a way to try esbuild live on esbuild's website without installing it: https://esbuild.github.io/try/. In addition to being able to more easily evaluate esbuild, this should also make it more efficient to generate esbuild bug reports. For example, you can use it to compare the behavior of different versions of esbuild on the same input. The state of the page is stored in the URL for easy sharing. Many thanks to @hyrious for creating https://hyrious.me/esbuild-repl/, which was the main inspiration for this addition to esbuild's website.

  Two forms of build options are supported: either CLI-style (example) or JS-style (example). Both are converted into a JS object that's passed to esbuild's WebAssembly API. The CLI-style argument parser is a custom one that simulates shell quoting rules, and the JS-style argument parser is also custom and parses a superset of JSON (basically JSON5 + regular expressions). So argument parsing is an approximate simulation of what happens for real but hopefully it should be close enough.

• Changes to esbuild's tsconfig.json support (#3019):

  This release makes the following changes to esbuild's tsconfig.json support:

  • Using experimental decorators now requires "experimentalDecorators": true (#104)

    Previously esbuild would always compile decorators in TypeScript code using TypeScript's experimental decorator transform. Now that standard JavaScript decorators are close to being finalized, esbuild will now require you to use "experimentalDecorators": true to do this. This new requirement makes it possible for esbuild to introduce a transform for standard JavaScript decorators in TypeScript code in the future. Such a transform has not been implemented yet, however.

  • TypeScript's target no longer affects esbuild's target (#2628)

    Some people requested that esbuild support TypeScript's target setting, so support for it was added (in version 0.12.4). However, esbuild supports reading from multiple tsconfig.json files within a single build, which opens up the possibility that different files in the build have different language targets configured. There isn't really any reason to do this and it can lead to unexpected results. So with this release, the target setting in tsconfig.json will no longer affect esbuild's own target setting. You will have to use esbuild's own target setting instead (which is a single, global value).

  • TypeScript's jsx setting no longer causes esbuild to preserve JSX syntax (#2634)

    TypeScript has a setting called jsx that controls how to transform JSX into JS. The tool-agnostic transform is called react, and the React-specific transform is called react-jsx (or react-jsxdev). There is also a setting called preserve which indicates JSX should be passed through untransformed. Previously people would run esbuild with "jsx": "preserve" in their tsconfig.json files and then be surprised when esbuild preserved their JSX. So with this release, esbuild will now ignore "jsx": "preserve" in tsconfig.json files. If you want to preserve JSX syntax with esbuild, you now have to use --jsx=preserve.

    Note: Some people have suggested that esbuild's equivalent jsx setting override the one in tsconfig.json. However, some projects need to legitimately have different files within the same build use different transforms (i.e. react vs. react-jsx) and having esbuild's global jsx setting override tsconfig.json would prevent this from working. This release ignores "jsx": "preserve" but still allows other jsx values in tsconfig.json files to override esbuild's global jsx setting to keep the ability for multiple files within the same build to use different transforms.

  • useDefineForClassFields behavior has changed (#2584, #2993)

    Class fields in TypeScript look like this (x is a class field):

    class Foo {
      x = 123
    }

    TypeScript has legacy behavior that uses assignment semantics instead of define semantics for class fields when useDefineForClassFields is enabled (in which case class fields in TypeScript behave differently than they do in JavaScript, which is arguably "wrong").

    This legacy behavior exists because TypeScript added class fields to TypeScript before they were added to JavaScript. The TypeScript team decided to go with assignment semantics and shipped their implementation. Much later on TC39 decided to go with define semantics for class fields in JavaScript instead. This behaves differently if the base class has a setter with the same name:

    class Base {
      set x(_) {
        console.log('x:', _)
      }
    }
    
    // useDefineForClassFields: false
    class AssignSemantics extends Base {
      constructor() {
        super()
        this.x = 123
      }
    }
    
    // useDefineForClassFields: true
    class DefineSemantics extends Base {
      constructor() {
        super()
        Object.defineProperty(this, 'x', { value: 123 })
      }
    }
    
    console.log(
      new AssignSemantics().x, // Calls the setter
      new DefineSemantics().x // Doesn't call the setter
    )

    When you run tsc, the value of useDefineForClassFields defaults to false when it's not specified and the target in tsconfig.json is present but earlier than ES2022. This sort of makes sense because the class field language feature was added in ES2022, so before ES2022 class fields didn't exist (and thus TypeScript's legacy behavior is active). However, TypeScript's target setting currently defaults to ES3 which unfortunately means that the useDefineForClassFields setting currently defaults to false (i.e. to "wrong"). In other words if you run tsc with all default settings, class fields will behave incorrectly.

    Previously esbuild tried to do what tsc did. That meant esbuild's version of useDefineForClassFields was false by default, and was also false if esbuild's --target= was present but earlier than es2022. However, TypeScript's legacy class field behavior is becoming increasingly irrelevant and people who expect class fields in TypeScript to work like they do in JavaScript are confused when they use esbuild with default settings. It's also confusing that the behavior of class fields would change if you changed the language target (even though that's exactly how TypeScript works).

    So with this release, esbuild will now only use the information in tsconfig.json to determine whether useDefineForClassFields is true or not. Specifically useDefineForClassFields will be respected if present, otherwise it will be false if target is present in tsconfig.json and is ES2021 or earlier, otherwise it will be true. Targets passed to esbuild's --target= setting will no longer affect useDefineForClassFields.

    Note that this means different directories in your build can have different values for this setting since esbuild allows different directories to have different tsconfig.json files within the same build. This should let you migrate your code one directory at a time without esbuild's --target= setting affecting the semantics of your code.

  • Add support for verbatimModuleSyntax from TypeScript 5.0

    TypeScript 5.0 added a new option called verbatimModuleSyntax that deprecates and replaces two older options, preserveValueImports and importsNotUsedAsValues. Setting verbatimModuleSyntax to true in tsconfig.json tells esbuild to not drop unused import statements. Specifically esbuild now treats "verbatimModuleSyntax": true as if you had specified both "preserveValueImports": true and "importsNotUsedAsValues": "preserve".

  • Add multiple inheritance for tsconfig.json from TypeScript 5.0

    TypeScript 5.0 now allows multiple inheritance for tsconfig.json files. You can now pass an array of filenames via the extends parameter and your tsconfig.json will start off containing properties from all of those configuration files, in order. This release of esbuild adds support for this new TypeScript fe...

v0.17.19

• Fix CSS transform bugs with nested selectors that start with a combinator (#3096)

  This release fixes several bugs regarding transforming nested CSS into non-nested CSS for older browsers. The bugs were due to lack of test coverage for nested selectors with more than one compound selector where they all start with the same combinator. Here's what some problematic cases look like before and after these fixes:

  /* Original code */
  .foo {
    > &a,
    > &b {
      color: red;
    }
  }
  .bar {
    > &a,
    + &b {
      color: green;
    }
  }
  
  /* Old output (with --target=chrome90) */
  .foo :is(> .fooa, > .foob) {
    color: red;
  }
  .bar :is(> .bara, + .barb) {
    color: green;
  }
  
  /* New output (with --target=chrome90) */
  .foo > :is(a.foo, b.foo) {
    color: red;
  }
  .bar > a.bar,
  .bar + b.bar {
    color: green;
  }

• Fix bug with TypeScript parsing of instantiation expressions followed by = (#3111)

  This release fixes esbuild's TypeScript-to-JavaScript conversion code in the case where a potential instantiation expression is followed immediately by a = token (such that the trailing > becomes a >= token). Previously esbuild considered that to still be an instantiation expression, but the official TypeScript compiler considered it to be a >= operator instead. This release changes esbuild's interpretation to match TypeScript. This edge case currently appears to be problematic for other TypeScript-to-JavaScript converters as well:

  Original code	TypeScript	esbuild 0.17.18	esbuild 0.17.19	Sucrase	Babel
  x<y>=a<b<c>>()	x<y>=a();	x=a();	x<y>=a();	x=a()	Invalid left-hand side in assignment expression

• Avoid removing unrecognized directives from the directive prologue when minifying (#3115)

  The directive prologue in JavaScript is a sequence of top-level string expressions that come before your code. The only directives that JavaScript engines currently recognize are use strict and sometimes use asm. However, the people behind React have made up their own directive for their own custom dialect of JavaScript. Previously esbuild only preserved the use strict directive when minifying, although you could still write React JavaScript with esbuild using something like --banner:js="'your directive here';". With this release, you can now put arbitrary directives in the entry point and esbuild will preserve them in its minified output:

  // Original code
  'use wtf'; console.log(123)
  
  // Old output (with --minify)
  console.log(123);
  
  // New output (with --minify)
  "use wtf";console.log(123);

  Note that this means esbuild will no longer remove certain stray top-level strings when minifying. This behavior is an intentional change because these stray top-level strings are actually part of the directive prologue, and could potentially have semantics assigned to them (as was the case with React).

• Improved minification of binary shift operators

  With this release, esbuild's minifier will now evaluate the << and >>> operators if the resulting code would be shorter:

  // Original code
  console.log(10 << 10, 10 << 20, -123 >>> 5, -123 >>> 10);
  
  // Old output (with --minify)
  console.log(10<<10,10<<20,-123>>>5,-123>>>10);
  
  // New output (with --minify)
  console.log(10240,10<<20,-123>>>5,4194303);

v0.17.18

• Fix non-default JSON import error with export {} from (#3070)

  This release fixes a bug where esbuild incorrectly identified statements of the form export { default as x } from "y" assert { type: "json" } as a non-default import. The bug did not affect code of the form import { default as x } from ... (only code that used the export keyword).

• Fix a crash with an invalid subpath import (#3067)

  Previously esbuild could crash when attempting to generate a friendly error message for an invalid subpath import (i.e. an import starting with #). This happened because esbuild originally only supported the exports field and the code for that error message was not updated when esbuild later added support for the imports field. This crash has been fixed.

v0.17.17

• Fix CSS nesting transform for top-level & (#3052)

  Previously esbuild could crash with a stack overflow when lowering CSS nesting rules with a top-level &, such as in the code below. This happened because esbuild's CSS nesting transform didn't handle top-level &, causing esbuild to inline the top-level selector into itself. This release handles top-level & by replacing it with the :scope pseudo-class:

  /* Original code */
  &,
  a {
    .b {
      color: red;
    }
  }
  
  /* New output (with --target=chrome90) */
  :is(:scope, a) .b {
    color: red;
  }

• Support exports in package.json for extends in tsconfig.json (#3058)

  TypeScript 5.0 added the ability to use extends in tsconfig.json to reference a path in a package whose package.json file contains an exports map that points to the correct location. This doesn't automatically work in esbuild because tsconfig.json affects esbuild's path resolution, so esbuild's normal path resolution logic doesn't apply.

  This release adds support for doing this by adding some additional code that attempts to resolve the extends path using the exports field. The behavior should be similar enough to esbuild's main path resolution logic to work as expected.

  Note that esbuild always treats this extends import as a require() import since that's what TypeScript appears to do. Specifically the require condition will be active and the import condition will be inactive.

• Fix watch mode with NODE_PATH (#3062)

  Node has a rarely-used feature where you can extend the set of directories that node searches for packages using the NODE_PATH environment variable. While esbuild supports this too, previously a bug prevented esbuild's watch mode from picking up changes to imported files that were contained directly in a NODE_PATH directory. You're supposed to use NODE_PATH for packages, but some people abuse this feature by putting files in that directory instead (e.g. node_modules/some-file.js instead of node_modules/some-pkg/some-file.js). The watch mode bug happens when you do this because esbuild first tries to read some-file.js as a directory and then as a file. Watch mode was incorrectly waiting for some-file.js to become a valid directory. This release fixes this edge case bug by changing watch mode to watch some-file.js as a file when this happens.