evanw/esbuild (esbuild)
### [`v0.21.4`](https://togithub.com/evanw/esbuild/blob/HEAD/CHANGELOG.md#0214)
[Compare Source](https://togithub.com/evanw/esbuild/compare/v0.21.3...v0.21.4)
- Update support for import assertions and import attributes in node ([#3778](https://togithub.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://togithub.com/evanw/esbuild/issues/3416), [#3425](https://togithub.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://togithub.com/evanw/esbuild/issues/3384), [#3639](https://togithub.com/evanw/esbuild/issues/3639), [#3646](https://togithub.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://togithub.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://togithub.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`](https://togithub.com/evanw/esbuild/blob/HEAD/CHANGELOG.md#0213)
[Compare Source](https://togithub.com/evanw/esbuild/compare/v0.21.2...v0.21.3)
- Implement the decorator metadata proposal ([#3760](https://togithub.com/evanw/esbuild/issues/3760))
This release implements the [decorator metadata proposal](https://togithub.com/tc39/proposal-decorator-metadata), which is a sub-proposal of the [decorators proposal](https://togithub.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://togithub.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://togithub.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`](https://togithub.com/evanw/esbuild/blob/HEAD/CHANGELOG.md#0212)
[Compare Source](https://togithub.com/evanw/esbuild/compare/v0.21.1...v0.21.2)
- Correct `this` in field and accessor decorators ([#3761](https://togithub.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://togithub.com/evanw/esbuild/issues/3762))
TypeScript recently [added `es2023`](https://togithub.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`](https://togithub.com/evanw/esbuild/blob/HEAD/CHANGELOG.md#0211)
[Compare Source](https://togithub.com/evanw/esbuild/compare/v0.21.0...v0.21.1)
- Fix a regression with `--keep-names` ([#3756](https://togithub.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`](https://togithub.com/evanw/esbuild/blob/HEAD/CHANGELOG.md#0210)
[Compare Source](https://togithub.com/evanw/esbuild/compare/v0.20.2...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://togithub.com/evanw/esbuild/issues/104))
With this release, esbuild now contains an implementation of the upcoming [JavaScript decorators proposal](https://togithub.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`](https://togithub.com/evanw/esbuild/blob/HEAD/CHANGELOG.md#0202)
[Compare Source](https://togithub.com/evanw/esbuild/compare/v0.20.1...v0.20.2)
- Support TypeScript experimental decorators on `abstract` class fields ([#3684](https://togithub.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://togithub.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)
(() => {
//
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)
(() => {
//
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://togithub.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://togithub.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://togithub.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://togithub.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.
### [`v0.20.1`](https://togithub.com/evanw/esbuild/blob/HEAD/CHANGELOG.md#0201)
[Compare Source](https://togithub.com/evanw/esbuild/compare/v0.20.0...v0.20.1)
- Fix a bug with the CSS nesting transform ([#3648](https://togithub.com/evanw/esbuild/issues/3648))
This release fixes a bug with the CSS nesting transform for older browsers where the generated CSS could be incorrect if a selector list contained a pseudo element followed by another selector. The bug was caused by incorrectly mutating the parent rule's selector list when filtering out pseudo elements for the child rules:
```css
/* Original code */
.foo {
&:after,
& .bar {
color: red;
}
}
/* Old output (with --supported:nesting=false) */
.foo .bar,
.foo .bar {
color: red;
}
/* New output (with --supported:nesting=false) */
.foo:after,
.foo .bar {
color: red;
}
```
- Constant folding for JavaScript inequality operators ([#3645](https://togithub.com/evanw/esbuild/issues/3645))
This release introduces constant folding for the `< > <= >=` operators. The minifier will now replace these operators with `true` or `false` when both sides are compile-time numeric or string constants:
```js
// Original code
console.log(1 < 2, '🍕' > '🧀')
// Old output (with --minify)
console.log(1<2,"🍕">"🧀");
// New output (with --minify)
console.log(!0,!1);
```
- Better handling of `__proto__` edge cases ([#3651](https://togithub.com/evanw/esbuild/pull/3651))
JavaScript object literal syntax contains a special case where a non-computed property with a key of `__proto__` sets the prototype of the object. This does not apply to computed properties or to properties that use the shorthand property syntax introduced in ES6. Previously esbuild didn't correctly preserve the "sets the prototype" status of properties inside an object literal, meaning a property that sets the prototype could accidentally be transformed into one that doesn't and vice versa. This has now been fixed:
```js
// Original code
function foo(__proto__) {
return { __proto__: __proto__ } // Note: sets the prototype
}
function bar(__proto__, proto) {
{
let __proto__ = proto
return { __proto__ } // Note: doesn't set the prototype
}
}
// Old output
function foo(__proto__) {
return { __proto__ }; // Note: no longer sets the prototype (WRONG)
}
function bar(__proto__, proto) {
{
let __proto__2 = proto;
return { __proto__: __proto__2 }; // Note: now sets the prototype (WRONG)
}
}
// New output
function foo(__proto__) {
return { __proto__: __proto__ }; // Note: sets the prototype (correct)
}
function bar(__proto__, proto) {
{
let __proto__2 = proto;
return { ["__proto__"]: __proto__2 }; // Note: doesn't set the prototype (correct)
}
}
```
- Fix cross-platform non-determinism with CSS color space transformations ([#3650](https://togithub.com/evanw/esbuild/issues/3650))
The Go compiler takes advantage of "fused multiply and add" (FMA) instructions on certain processors which do the operation `x*y + z` without intermediate rounding. This causes esbuild's CSS color space math to differ on different processors (currently `ppc64le` and `s390x`), which breaks esbuild's guarantee of deterministic output. To avoid this, esbuild's color space math now inserts a `float64()` cast around every single math operation. This tells the Go compiler not to use the FMA optimization.
- Fix a crash when resolving a path from a directory that doesn't exist ([#3634](https://togithub.com/evanw/esbuild/issues/3634))
This release fixes a regression where esbuild could crash when resolving an absolute path if the source directory for the path resolution operation doesn't exist. While this situation doesn't normally come up, it could come up when running esbuild concurrently with another operation that mutates the file system as esbuild is doing a build (such as using `git` to switch branches). The underlying problem was a regression that was introduced in version 0.18.0.
### [`v0.20.0`](https://togithub.com/evanw/esbuild/blob/HEAD/CHANGELOG.md#0200)
[Compare Source](https://togithub.com/evanw/esbuild/compare/v0.19.12...v0.20.0)
**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 `^0.19.0` or `~0.19.0`. See npm's documentation about [semver](https://docs.npmjs.com/cli/v6/using-npm/semver/) for more information.
This time there is only one breaking change, and it only matters for people using Deno. Deno tests that use esbuild will now fail unless you make the change described below.
- Work around API deprecations in Deno 1.40.x ([#3609](https://togithub.com/evanw/esbuild/issues/3609), [#3611](https://togithub.com/evanw/esbuild/pull/3611))
[Deno 1.40.0](https://deno.com/blog/v1.40) was just released and introduced run-time warnings about certain APIs that esbuild uses. With this release, esbuild will work around these run-time warnings by using newer APIs if they are present and falling back to the original APIs otherwise. This should avoid the warnings without breaking compatibility with older versions of Deno.
Unfortunately, doing this introduces a breaking change. The newer child process APIs lack a way to synchronously terminate esbuild's child process, so calling `esbuild.stop()` from within a Deno test is no longer sufficient to prevent Deno from failing a test that uses esbuild's API (Deno fails tests that create a child process without killing it before the test ends). To work around this, esbuild's `stop()` function has been changed to return a promise, and you now have to change `esbuild.stop()` to `await esbuild.stop()` in all of your Deno tests.
- Reorder implicit file extensions within `node_modules` ([#3341](https://togithub.com/evanw/esbuild/issues/3341), [#3608](https://togithub.com/evanw/esbuild/issues/3608))
In [version 0.18.0](https://togithub.com/evanw/esbuild/releases/v0.18.0), esbuild changed the behavior of implicit file extensions within `node_modules` directories (i.e. in published packages) to prefer `.js` over `.ts` even when the `--resolve-extensions=` order prefers `.ts` over `.js` (which it does by default). However, doing that also accidentally made esbuild prefer `.css` over `.ts`, which caused problems for people that published packages containing both TypeScript and CSS in files with the same name.
With this release, esbuild will reorder TypeScript file extensions immediately after the last JavaScript file extensions in the implicit file extension order instead of putting them at the end of the order. Specifically the default implicit file extension order is `.tsx,.ts,.jsx,.js,.css,.json` which used to become `.jsx,.js,.css,.json,.tsx,.ts` in `node_modules` directories. With this release it will now become `.jsx,.js,.tsx,.ts,.css,.json` instead.
Why even rewrite the implicit file extension order at all? One reason is because the `.js` file is more likely to behave correctly than the `.ts` file. The behavior of the `.ts` file may depend on `tsconfig.json` and the `tsconfig.json` file may not even be published, or may use `extends` to refer to a base `tsconfig.json` file that wasn't published. People can get into this situation when they forget to add all `.ts` files to their `.npmignore` file before publishing to npm. Picking `.js` over `.ts` helps make it more likely that resulting bundle will behave correctly.
### [`v0.19.12`](https://togithub.com/evanw/esbuild/blob/HEAD/CHANGELOG.md#01912)
[Compare Source](https://togithub.com/evanw/esbuild/compare/v0.19.11...v0.19.12)
- The "preserve" JSX mode now preserves JSX text verbatim ([#3605](https://togithub.com/evanw/esbuild/issues/3605))
The [JSX specification](https://facebook.github.io/jsx/) deliberately doesn't specify how JSX text is supposed to be interpreted and there is no canonical way to interpret JSX text. Two most popular interpretations are Babel and TypeScript. Yes [they are different](https://twitter.com/jarredsumner/status/1456118847937781764) (esbuild [deliberately follows TypeScript](https://twitter.com/evanwallace/status/1456122279453208576) by the way).
Previously esbuild normalized text to the TypeScript interpretation when the "preserve" JSX mode is active. However, "preserve" should arguably reproduce the original JSX text verbatim so that whatever JSX transform runs after esbuild is free to interpret it however it wants. So with this release, esbuild will now pass JSX text through unmodified:
```jsx
// Original code
let el =
some text
{foo}
more text
// Old output (with --loader=jsx --jsx=preserve)
let el =
{" some text"}
{foo}
{"more text "}
;
// New output (with --loader=jsx --jsx=preserve)
let el = some text
{foo}
more text ;
```
- Allow JSX elements as JSX attribute values
JSX has an obscure feature where you can use JSX elements in attribute position without surrounding them with `{...}`. It looks like this:
```jsx
let el =
/>;
```
I think I originally didn't implement it even though it's part of the [JSX specification](https://facebook.github.io/jsx/) because it previously didn't work in TypeScript (and potentially also in Babel?). However, support for it was [silently added in TypeScript 4.8](https://togithub.com/microsoft/TypeScript/pull/47994) without me noticing and Babel has also since fixed their [bugs regarding this feature](https://togithub.com/babel/babel/pull/6006). So I'm adding it to esbuild too now that I know it's widely supported.
Keep in mind that there is some ongoing discussion about [removing this feature from JSX](https://togithub.com/facebook/jsx/issues/53). I agree that the syntax seems out of place (it does away with the elegance of "JSX is basically just XML with `{...}` escapes" for something arguably harder to read, which doesn't seem like a good trade-off), but it's in the specification and TypeScript and Babel both implement it so I'm going to have esbuild implement it too. However, I reserve the right to remove it from esbuild if it's ever removed from the specification in the future. So use it with caution.
- Fix a bug with TypeScript type parsing ([#3574](https://togithub.com/evanw/esbuild/issues/3574))
This release fixes a bug with esbuild's TypeScript parser where a conditional type containing a union type that ends with an infer type that ends with a constraint could fail to parse. This was caused by the "don't parse a conditional type" flag not getting passed through the union type parser. Here's an example of valid TypeScript code that previously failed to parse correctly:
```ts
type InferUnion = T extends { a: infer U extends number } | infer U extends number ? U : never
```
### [`v0.19.11`](https://togithub.com/evanw/esbuild/blob/HEAD/CHANGELOG.md#01911)
[Compare Source](https://togithub.com/evanw/esbuild/compare/v0.19.10...v0.19.11)
- Fix TypeScript-specific class transform edge case ([#3559](https://togithub.com/evanw/esbuild/issues/3559))
The previous release introduced an optimization that avoided transforming `super()` in the class constructor for TypeScript code compiled with `useDefineForClassFields` set to `false` if all class instance fields have no initializers. The rationale was that in this case, all class instance fields are omitted in the output so no changes to the constructor are needed. However, if all of this is the case *and* there are `#private` instance fields with initializers, those private instance field initializers were still being moved into the constructor. This was problematic because they were being inserted before the call to `super()` (since `super()` is now no longer transformed in that case). This release introduces an additional optimization that avoids moving the private instance field initializers into the constructor in this edge case, which generates smaller code, matches the TypeScript compiler's output more closely, and avoids this bug:
```ts
// Original code
class Foo extends Bar {
#private = 1;
public: any;
constructor() {
super();
}
}
// Old output (with esbuild v0.19.9)
class Foo extends Bar {
constructor() {
super();
this.#private = 1;
}
#private;
}
// Old output (with esbuild v0.19.10)
class Foo extends Bar {
constructor() {
this.#private = 1;
super();
}
#private;
}
// New output
class Foo extends Bar {
#private = 1;
constructor() {
super();
}
}
```
- Minifier: allow reording a primitive past a side-effect ([#3568](https://togithub.com/evanw/esbuild/issues/3568))
The minifier previously allowed reordering a side-effect past a primitive, but didn't handle the case of reordering a primitive past a side-effect. This additional case is now handled:
```js
// Original code
function f() {
let x = false;
let y = x;
const boolean = y;
let frag = $.template(`
hello world
`);
return frag;
}
// Old output (with --minify)
function f(){const e=!1;return $.template(`
hello world
`)}
// New output (with --minify)
function f(){return $.template('
hello world
')}
```
- Minifier: consider properties named using known `Symbol` instances to be side-effect free ([#3561](https://togithub.com/evanw/esbuild/issues/3561))
Many things in JavaScript can have side effects including property accesses and ToString operations, so using a symbol such as `Symbol.iterator` as a computed property name is not obviously side-effect free. This release adds a special case for known `Symbol` instances so that they are considered side-effect free when used as property names. For example, this class declaration will now be considered side-effect free:
```js
class Foo {
*[Symbol.iterator]() {
}
}
```
- Provide the `stop()` API in node to exit esbuild's child process ([#3558](https://togithub.com/evanw/esbuild/issues/3558))
You can now call `stop()` in esbuild's node API to exit esbuild's child process to reclaim the resources used. It only makes sense to do this for a long-lived node process when you know you will no longer be making any more esbuild API calls. It is not necessary to call this to allow node to exit, and it's advantageous to not call this in between calls to esbuild's API as sharing a single long-lived esbuild child process is more efficient than re-creating a new esbuild child process for every API call. This API call used to exist but was removed in [version 0.9.0](https://togithub.com/evanw/esbuild/releases/v0.9.0). This release adds it back due to a user request.
### [`v0.19.10`](https://togithub.com/evanw/esbuild/blob/HEAD/CHANGELOG.md#01910)
[Compare Source](https://togithub.com/evanw/esbuild/compare/v0.19.9...v0.19.10)
- Fix glob imports in TypeScript files ([#3319](https://togithub.com/evanw/esbuild/issues/3319))
This release fixes a problem where bundling a TypeScript file containing a glob import could emit a call to a helper function that doesn't exist. The problem happened because esbuild's TypeScript transformation removes unused imports (which is required for correctness, as they may be type-only imports) and esbuild's glob import transformation wasn't correctly marking the imported helper function as used. This wasn't caught earlier because most of esbuild's glob import tests were written in JavaScript, not in TypeScript.
- Fix `require()` glob imports with bundling disabled ([#3546](https://togithub.com/evanw/esbuild/issues/3546))
Previously `require()` calls containing glob imports were incorrectly transformed when bundling was disabled. All glob imports should only be transformed when bundling is enabled. This bug has been fixed.
- Fix a panic when transforming optional chaining with `define` ([#3551](https://togithub.com/evanw/esbuild/issues/3551), [#3554](https://togithub.com/evanw/esbuild/pull/3554))
This release fixes a case where esbuild could crash with a panic, which was triggered by using `define` to replace an expression containing an optional chain. Here is an example:
```js
// Original code
console.log(process?.env.SHELL)
// Old output (with --define:process.env={})
/* panic: Internal error (while parsing "") */
// New output (with --define:process.env={})
var define_process_env_default = {};
console.log(define_process_env_default.SHELL);
```
This fix was contributed by [@hi-ogawa](https://togithub.com/hi-ogawa).
- Work around a bug in node's CommonJS export name detector ([#3544](https://togithub.com/evanw/esbuild/issues/3544))
The export names of a CommonJS module are dynamically-determined at run time because CommonJS exports are properties on a mutable object. But the export names of an ES module are statically-determined at module instantiation time by using `import` and `export` syntax and cannot be changed at run time.
When you import a CommonJS module into an ES module in node, node scans over the source code to attempt to detect the set of export names that the CommonJS module will end up using. That statically-determined set of names is used as the set of names that the ES module is allowed to import at module instantiation time. However, this scan appears to have bugs (or at least, can cause false positives) because it doesn't appear to do any scope analysis. Node will incorrectly consider the module to export something even if the assignment is done to a local variable instead of to the module-level `exports` object. For example:
```js
// confuseNode.js
exports.confuseNode = function(exports) {
// If this local is called "exports", node incorrectly
// thinks this file has an export called "notAnExport".
exports.notAnExport = function() {
};
};
```
You can see that node incorrectly thinks the file `confuseNode.js` has an export called `notAnExport` when that file is loaded in an ES module context:
```console
$ node -e 'import("./confuseNode.js").then(console.log)'
[Module: null prototype] {
confuseNode: [Function (anonymous)],
default: { confuseNode: [Function (anonymous)] },
notAnExport: undefined
}
```
To avoid this, esbuild will now rename local variables that use the names `exports` and `module` when generating CommonJS output for the `node` platform.
- Fix the return value of esbuild's `super()` shim ([#3538](https://togithub.com/evanw/esbuild/issues/3538))
Some people write `constructor` methods that use the return value of `super()` instead of using `this`. This isn't too common because [TypeScript doesn't let you do that](https://togithub.com/microsoft/TypeScript/issues/37847) but it can come up when writing JavaScript. Previously esbuild's class lowering transform incorrectly transformed the return value of `super()` into `undefined`. With this release, the return value of `super()` will now be `this` instead:
```js
// Original code
class Foo extends Object {
field
constructor() {
console.log(typeof super())
}
}
new Foo
// Old output (with --target=es6)
class Foo extends Object {
constructor() {
var __super = (...args) => {
super(...args);
__publicField(this, "field");
};
console.log(typeof __super());
}
}
new Foo();
// New output (with --target=es6)
class Foo extends Object {
constructor() {
var __super = (...args) => {
super(...args);
__publicField(this, "field");
return this;
};
console.log(typeof __super());
}
}
new Foo();
```
- Terminate the Go GC when esbuild's `stop()` API is called ([#3552](https://togithub.com/evanw/esbuild/issues/3552))
If you use esbuild with WebAssembly and pass the `worker: false` flag to `esbuild.initialize()`, then esbuild will run the WebAssembly module on the main thread. If you do this within a Deno test and that test calls `esbuild.stop()` to clean up esbuild's resources, Deno may complain that a `setTimeout()` call lasted past the end of the test. This happens when the Go is in the middle of a garbage collection pass and has scheduled additional ongoing garbage collection work. Normally calling `esbuild.stop()` will terminate the web worker that the WebAssembly module runs in, which will terminate the Go GC, but that doesn't happen if you disable the web worker with `worker: false`.
With this release, esbuild will now attempt to terminate the Go GC in this edge case by calling `clearTimeout()` on these pending timeouts.
- Apply `/* @__NO_SIDE_EFFECTS__ */` on tagged template literals ([#3511](https://togithub.com/evanw/esbuild/issues/3511))
Tagged template literals that reference functions annotated with a `@__NO_SIDE_EFFECTS__` comment are now able to be removed via tree-shaking if the result is unused. This is a convention from [Rollup](https://togithub.com/rollup/rollup/pull/5024). Here is an example:
```js
// Original code
const html = /* @__NO_SIDE_EFFECTS__ */ (a, ...b) => ({ a, b })
html`remove`
x = html`keep`
// Old output (with --tree-shaking=true)
const html = /* @__NO_SIDE_EFFECTS__ */ (a, ...b) => ({ a, b });
html`remove`;
x = html`keep`;
// New output (with --tree-shaking=true)
const html = /* @__NO_SIDE_EFFECTS__ */ (a, ...b) => ({ a, b });
x = html`keep`;
```
Note that this feature currently only works within a single file, so it's not especially useful. This feature does not yet work across separate files. I still recommend using `@__PURE__` annotations instead of this feature, as they have wider tooling support. The drawback of course is that `@__PURE__` annotations need to be added at each call site, not at the declaration, and for non-call expressions such as template literals you need to wrap the expression in an IIFE (immediately-invoked function expression) to create a call expression to apply the `@__PURE__` annotation to.
- Publish builds for IBM AIX PowerPC 64-bit ([#3549](https://togithub.com/evanw/esbuild/issues/3549))
This release publishes a binary executable to npm for IBM AIX PowerPC 64-bit, which means that in theory esbuild can now be installed in that environment with `npm install esbuild`. This hasn't actually been tested yet. If you have access to such a system, it would be helpful to confirm whether or not doing this actually works.
### [`v0.19.9`](https://togithub.com/evanw/esbuild/blob/HEAD/CHANGELOG.md#0199)
[Compare Source](https://togithub.com/evanw/esbuild/compare/v0.19.8...v0.19.9)
- Add support for transforming new CSS gradient syntax for older browsers
The specification called [CSS Images Module Level 4](https://www.w3.org/TR/css-images-4/) introduces new CSS gradient syntax for customizing how the browser interpolates colors in between color stops. You can now control the color space that the interpolation happens in as well as (for "polar" color spaces) control whether hue angle interpolation happens clockwise or counterclockwise. You can read more about this in [Mozilla's blog post about new CSS gradient features](https://developer.mozilla.org/en-US/blog/css-color-module-level-4/).
With this release, esbuild will now automatically transform this syntax for older browsers in the `target` list. For example, here's a gradient that should appear as a rainbow in a browser that supports this new syntax:
```css
/* Original code */
.rainbow-gradient {
width: 100px;
height: 100px;
background: linear-gradient(in hsl longer hue, #7ff, #77f);
}
/* New output (with --target=chrome99) */
.rainbow-gradient {
width: 100px;
height: 100px;
background:
linear-gradient(
#77ffff,
#77ffaa 12.5%,
#77ff80 18.75%,
#84ff77 21.88%,
#99ff77 25%,
#eeff77 37.5%,
#fffb77 40.62%,
#ffe577 43.75%,
#ffbb77 50%,
#ff9077 56.25%,
#ff7b77 59.38%,
#ff7788 62.5%,
#ff77dd 75%,
#ff77f2 78.12%,
#f777ff 81.25%,
#cc77ff 87.5%,
#7777ff);
}
```
You can now use this syntax in your CSS source code and esbuild will automatically convert it to an equivalent gradient for older browsers. In addition, esbuild will now also transform "double position" and "transition hint" syntax for older browsers as appropriate:
```css
/* Original code */
.stripes {
width: 100px;
height: 100px;
background: linear-gradient(#e65 33%, #ff2 33% 67%, #99e 67%);
}
.glow {
width: 100px;
height: 100px;
background: radial-gradient(white 10%, 20%, black);
}
/* New output (with --target=chrome33) */
.stripes {
width: 100px;
height: 100px;
background:
linear-gradient(
#e65 33%,
#ff2 33%,
#ff2 67%,
#99e 67%);
}
.glow {
width: 100px;
height: 100px;
background:
radial-gradient(
#ffffff 10%,
#aaaaaa 12.81%,
#959595 15.62%,
#7b7b7b 21.25%,
#5a5a5a 32.5%,
#444444 43.75%,
#323232 55%,
#161616 77.5%,
#000000);
}
```
You can see visual examples of these new syntax features by looking at [esbuild's gradient transformation tests](https://esbuild.github.io/gradient-tests/).
If necessary, esbuild will construct a new gradient that approximates the original gradient by recursively splitting the interval in between color stops until the approximation error is within a small threshold. That is why the above output CSS contains many more color stops than the input CSS.
Note that esbuild deliberately *replaces* the original gradient with the approximation instead of inserting the approximation before the original gradient as a fallback. The latest version of Firefox has multiple gradient rendering bugs (including incorrect interpolation of partially-transparent colors and interpolating non-sRGB colors using the incorrect color space). If esbuild didn't replace the original gradient, then Firefox would use the original gradient instead of the fallback the appearance would be incorrect in Firefox. In other words, the latest version of Firefox supports modern gradient syntax but interprets it incorrectly.
- Add support for `color()`, `lab()`, `lch()`, `oklab()`, `oklch()`, and `hwb()` in CSS
CSS has recently added lots of new ways of specifying colors. You can read more about this in [Chrome's blog post about CSS color spaces](https://developer.chrome.com/docs/css-ui/high-definition-css-color-guide).
This release adds support for minifying colors that use the `color()`, `lab()`, `lch()`, `oklab()`, `oklch()`, or `hwb()` syntax and/or transforming these colors for browsers that don't support it yet:
```css
/* Original code */
div {
color: hwb(90deg 20% 40%);
background: color(display-p3 1 0 0);
}
/* New output (with --target=chrome99) */
div {
color: #669933;
background: #ff0f0e;
background: color(display-p3 1 0 0);
}
```
As you can see, colors outside of the sRGB color space such as `color(display-p3 1 0 0)` are mapped back into the sRGB gamut and inserted as a fallback for browsers that don't support the new color syntax.
- Allow empty type parameter lists in certain cases ([#3512](https://togithub.com/evanw/esbuild/issues/3512))
TypeScript allows interface declarations and type aliases to have empty type parameter lists. Previously esbuild didn't handle this edge case but with this release, esbuild will now parse this syntax:
```ts
interface Foo<> {}
type Bar<> = {}
```
This fix was contributed by [@magic-akari](https://togithub.com/magic-akari).
### [`v0.19.8`](https://togithub.com/evanw/esbuild/blob/HEAD/CHANGELOG.md#0198)
[Compare Source](https://togithub.com/evanw/esbuild/compare/v0.19.7...v0.19.8)
- Add a treemap chart to esbuild's bundle analyzer ([#2848](https://togithub.com/evanw/esbuild/issues/2848))
The bundler analyzer on esbuild's website (https://esbuild.github.io/analyze/) now has a treemap chart type in addition to the two existing chart types (sunburst and flame). This should be more familiar for people coming from other similar tools, as well as make better use of large screens.
- Allow decorators after the `export` keyword ([#104](https://togithub.com/evanw/esbuild/issues/104))
Previously esbuild's decorator parser followed the original behavior of TypeScript's experimental decorators feature, which only allowed decorators to come before the `export` keyword. However, the upcoming JavaScript decorators feature also allows decorators to come after the `export` keyword. And with TypeScript 5.0, TypeScript now also allows experimental decorators to come after the `export` keyword too. So esbuild now allows this as well:
```js
// This old syntax has always been permitted:
@decorator export class Foo {}
@decorator export default class Foo {}
// This new syntax is now permitted too:
e
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This PR contains the following updates:
0.17.3->0.21.4Release Notes
evanw/esbuild (esbuild)
### [`v0.21.4`](https://togithub.com/evanw/esbuild/blob/HEAD/CHANGELOG.md#0214) [Compare Source](https://togithub.com/evanw/esbuild/compare/v0.21.3...v0.21.4) - Update support for import assertions and import attributes in node ([#3778](https://togithub.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://togithub.com/evanw/esbuild/issues/3416), [#3425](https://togithub.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://togithub.com/evanw/esbuild/issues/3384), [#3639](https://togithub.com/evanw/esbuild/issues/3639), [#3646](https://togithub.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://togithub.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://togithub.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`](https://togithub.com/evanw/esbuild/blob/HEAD/CHANGELOG.md#0213) [Compare Source](https://togithub.com/evanw/esbuild/compare/v0.21.2...v0.21.3) - Implement the decorator metadata proposal ([#3760](https://togithub.com/evanw/esbuild/issues/3760)) This release implements the [decorator metadata proposal](https://togithub.com/tc39/proposal-decorator-metadata), which is a sub-proposal of the [decorators proposal](https://togithub.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://togithub.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://togithub.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`](https://togithub.com/evanw/esbuild/blob/HEAD/CHANGELOG.md#0212) [Compare Source](https://togithub.com/evanw/esbuild/compare/v0.21.1...v0.21.2) - Correct `this` in field and accessor decorators ([#3761](https://togithub.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://togithub.com/evanw/esbuild/issues/3762)) TypeScript recently [added `es2023`](https://togithub.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`](https://togithub.com/evanw/esbuild/blob/HEAD/CHANGELOG.md#0211) [Compare Source](https://togithub.com/evanw/esbuild/compare/v0.21.0...v0.21.1) - Fix a regression with `--keep-names` ([#3756](https://togithub.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`](https://togithub.com/evanw/esbuild/blob/HEAD/CHANGELOG.md#0210) [Compare Source](https://togithub.com/evanw/esbuild/compare/v0.20.2...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://togithub.com/evanw/esbuild/issues/104)) With this release, esbuild now contains an implementation of the upcoming [JavaScript decorators proposal](https://togithub.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`](https://togithub.com/evanw/esbuild/blob/HEAD/CHANGELOG.md#0202) [Compare Source](https://togithub.com/evanw/esbuild/compare/v0.20.1...v0.20.2) - Support TypeScript experimental decorators on `abstract` class fields ([#3684](https://togithub.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://togithub.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) (() => { //hello world
`); return frag; } // Old output (with --minify) function f(){const e=!1;return $.template(`hello world
`)} // New output (with --minify) function f(){return $.template('hello world
')} ``` - Minifier: consider properties named using known `Symbol` instances to be side-effect free ([#3561](https://togithub.com/evanw/esbuild/issues/3561)) Many things in JavaScript can have side effects including property accesses and ToString operations, so using a symbol such as `Symbol.iterator` as a computed property name is not obviously side-effect free. This release adds a special case for known `Symbol` instances so that they are considered side-effect free when used as property names. For example, this class declaration will now be considered side-effect free: ```js class Foo { *[Symbol.iterator]() { } } ``` - Provide the `stop()` API in node to exit esbuild's child process ([#3558](https://togithub.com/evanw/esbuild/issues/3558)) You can now call `stop()` in esbuild's node API to exit esbuild's child process to reclaim the resources used. It only makes sense to do this for a long-lived node process when you know you will no longer be making any more esbuild API calls. It is not necessary to call this to allow node to exit, and it's advantageous to not call this in between calls to esbuild's API as sharing a single long-lived esbuild child process is more efficient than re-creating a new esbuild child process for every API call. This API call used to exist but was removed in [version 0.9.0](https://togithub.com/evanw/esbuild/releases/v0.9.0). This release adds it back due to a user request. ### [`v0.19.10`](https://togithub.com/evanw/esbuild/blob/HEAD/CHANGELOG.md#01910) [Compare Source](https://togithub.com/evanw/esbuild/compare/v0.19.9...v0.19.10) - Fix glob imports in TypeScript files ([#3319](https://togithub.com/evanw/esbuild/issues/3319)) This release fixes a problem where bundling a TypeScript file containing a glob import could emit a call to a helper function that doesn't exist. The problem happened because esbuild's TypeScript transformation removes unused imports (which is required for correctness, as they may be type-only imports) and esbuild's glob import transformation wasn't correctly marking the imported helper function as used. This wasn't caught earlier because most of esbuild's glob import tests were written in JavaScript, not in TypeScript. - Fix `require()` glob imports with bundling disabled ([#3546](https://togithub.com/evanw/esbuild/issues/3546)) Previously `require()` calls containing glob imports were incorrectly transformed when bundling was disabled. All glob imports should only be transformed when bundling is enabled. This bug has been fixed. - Fix a panic when transforming optional chaining with `define` ([#3551](https://togithub.com/evanw/esbuild/issues/3551), [#3554](https://togithub.com/evanw/esbuild/pull/3554)) This release fixes a case where esbuild could crash with a panic, which was triggered by using `define` to replace an expression containing an optional chain. Here is an example: ```js // Original code console.log(process?.env.SHELL) // Old output (with --define:process.env={}) /* panic: Internal error (while parsing "Configuration
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