evanw/esbuild (esbuild)
### [`v0.23.0`](https://togithub.com/evanw/esbuild/blob/HEAD/CHANGELOG.md#0230)
[Compare Source](https://togithub.com/evanw/esbuild/compare/v0.22.0...v0.23.0)
***This release deliberately contains backwards-incompatible changes.*** To avoid automatically picking up releases like this, you should either be pinning the exact version of `esbuild` in your `package.json` file (recommended) or be using a version range syntax that only accepts patch upgrades such as `^0.22.0` or `~0.22.0`. See npm's documentation about [semver](https://docs.npmjs.com/cli/v6/using-npm/semver/) for more information.
- Revert the recent change to avoid bundling dependencies for node ([#3819](https://togithub.com/evanw/esbuild/issues/3819))
This release reverts the recent change in version 0.22.0 that made `--packages=external` the default behavior with `--platform=node`. The default is now back to `--packages=bundle`.
I've just been made aware that Amazon doesn't pin their dependencies in their "AWS CDK" product, which means that whenever esbuild publishes a new release, many people (potentially everyone?) using their SDK around the world instantly starts using it without Amazon checking that it works first. This change in version 0.22.0 happened to break their SDK. I'm amazed that things haven't broken before this point. This revert attempts to avoid these problems for Amazon's customers. Hopefully Amazon will pin their dependencies in the future.
In addition, this is probably a sign that esbuild is used widely enough that it now needs to switch to a more complicated release model. I may have esbuild use a beta channel model for further development.
- Fix preserving collapsed JSX whitespace ([#3818](https://togithub.com/evanw/esbuild/issues/3818))
When transformed, certain whitespace inside JSX elements is ignored completely if it collapses to an empty string. However, the whitespace should only be ignored if the JSX is being transformed, not if it's being preserved. This release fixes a bug where esbuild was previously incorrectly ignoring collapsed whitespace with `--jsx=preserve`. Here is an example:
```jsx
// Original code
// Old output (with --jsx=preserve)
;
// New output (with --jsx=preserve)
;
```
### [`v0.22.0`](https://togithub.com/evanw/esbuild/blob/HEAD/CHANGELOG.md#0220)
[Compare Source](https://togithub.com/evanw/esbuild/compare/v0.21.5...v0.22.0)
**This release deliberately contains backwards-incompatible changes.** To avoid automatically picking up releases like this, you should either be pinning the exact version of `esbuild` in your `package.json` file (recommended) or be using a version range syntax that only accepts patch upgrades such as `^0.21.0` or `~0.21.0`. See npm's documentation about [semver](https://docs.npmjs.com/cli/v6/using-npm/semver/) for more information.
- Omit packages from bundles by default when targeting node ([#1874](https://togithub.com/evanw/esbuild/issues/1874), [#2830](https://togithub.com/evanw/esbuild/issues/2830), [#2846](https://togithub.com/evanw/esbuild/issues/2846), [#2915](https://togithub.com/evanw/esbuild/issues/2915), [#3145](https://togithub.com/evanw/esbuild/issues/3145), [#3294](https://togithub.com/evanw/esbuild/issues/3294), [#3323](https://togithub.com/evanw/esbuild/issues/3323), [#3582](https://togithub.com/evanw/esbuild/issues/3582), [#3809](https://togithub.com/evanw/esbuild/issues/3809), [#3815](https://togithub.com/evanw/esbuild/issues/3815))
This breaking change is an experiment. People are commonly confused when using esbuild to bundle code for node (i.e. for `--platform=node`) because some packages may not be intended for bundlers, and may use node-specific features that don't work with a bundler. Even though esbuild's "getting started" instructions say to use `--packages=external` to work around this problem, many people don't read the documentation and don't do this, and are then confused when it doesn't work. So arguably this is a bad default behavior for esbuild to have if people keep tripping over this.
With this release, esbuild will now omit packages from the bundle by default when the platform is `node` (i.e. the previous behavior of `--packages=external` is now the default in this case). *Note that your dependencies must now be present on the file system when your bundle is run.* If you don't want this behavior, you can do `--packages=bundle` to allow packages to be included in the bundle (i.e. the previous default behavior). Note that `--packages=bundle` doesn't mean all packages are bundled, just that packages are allowed to be bundled. You can still exclude individual packages from the bundle using `--external:` even when `--packages=bundle` is present.
The `--packages=` setting considers all import paths that "look like" package imports in the original source code to be package imports. Specifically import paths that don't start with a path segment of `/` or `.` or `..` are considered to be package imports. The only two exceptions to this rule are [subpath imports](https://nodejs.org/api/packages.html#subpath-imports) (which start with a `#` character) and TypeScript path remappings via `paths` and/or `baseUrl` in `tsconfig.json` (which are applied first).
- Drop support for older platforms ([#3802](https://togithub.com/evanw/esbuild/issues/3802))
This release drops support for the following operating systems:
- Windows 7
- Windows 8
- Windows Server 2008
- Windows Server 2012
This is because the Go programming language dropped support for these operating system versions in [Go 1.21](https://go.dev/doc/go1.21#windows), and this release updates esbuild from Go 1.20 to Go 1.22.
Note that this only affects the binary esbuild executables that are published to the `esbuild` npm package. It's still possible to compile esbuild's source code for these older operating systems. If you need to, you can compile esbuild for yourself using an older version of the Go compiler (before Go version 1.21). That might look something like this:
git clone https://github.com/evanw/esbuild.git
cd esbuild
go build ./cmd/esbuild
./esbuild.exe --version
In addition, this release increases the minimum required node version for esbuild's JavaScript API from node 12 to node 18. Node 18 is the oldest version of node that is still being supported (see node's [release schedule](https://nodejs.org/en/about/previous-releases) for more information). This increase is because of an incompatibility between the JavaScript that the Go compiler generates for the `esbuild-wasm` package and versions of node before node 17.4 (specifically the `crypto.getRandomValues` function).
- Update `await using` behavior to match TypeScript
TypeScript 5.5 subtly changes the way `await using` behaves. This release updates esbuild to match these changes in TypeScript. You can read more about these changes in [microsoft/TypeScript#58624](https://togithub.com/microsoft/TypeScript/pull/58624).
- Allow `es2024` as a target environment
The ECMAScript 2024 specification was just approved, so it has been added to esbuild as a possible compilation target. You can read more about the features that it adds here: . The only addition that's relevant for esbuild is the regular expression `/v` flag. With `--target=es2024`, regular expressions that use the `/v` flag will now be passed through untransformed instead of being transformed into a call to `new RegExp`.
- Publish binaries for OpenBSD on 64-bit ARM ([#3665](https://togithub.com/evanw/esbuild/issues/3665), [#3674](https://togithub.com/evanw/esbuild/pull/3674))
With this release, you should now be able to install the `esbuild` npm package in OpenBSD on 64-bit ARM, such as on an Apple device with an M1 chip.
This was contributed by [@ikmckenz](https://togithub.com/ikmckenz).
- Publish binaries for WASI (WebAssembly System Interface) preview 1 ([#3300](https://togithub.com/evanw/esbuild/issues/3300), [#3779](https://togithub.com/evanw/esbuild/pull/3779))
The upcoming WASI (WebAssembly System Interface) standard is going to be a way to run WebAssembly outside of a JavaScript host environment. In this scenario you only need a `.wasm` file without any supporting JavaScript code. Instead of JavaScript providing the APIs for the host environment, the WASI standard specifies a "system interface" that WebAssembly code can access directly (e.g. for file system access).
Development versions of the WASI specification are being released using preview numbers. The people behind WASI are currently working on preview 2 but the Go compiler has [released support for preview 1](https://go.dev/blog/wasi), which from what I understand is now considered an unsupported legacy release. However, some people have requested that esbuild publish binary executables that support WASI preview 1 so they can experiment with them.
This release publishes esbuild precompiled for WASI preview 1 to the `@esbuild/wasi-preview1` package on npm (specifically the file `@esbuild/wasi-preview1/esbuild.wasm`). This binary executable has not been tested and won't be officially supported, as it's for an old preview release of a specification that has since moved in another direction. If it works for you, great! If not, then you'll likely have to wait for the ecosystem to evolve before using esbuild with WASI. For example, it sounds like perhaps WASI preview 1 doesn't include support for opening network sockets so esbuild's local development server is unlikely to work with WASI preview 1.
- Warn about `onResolve` plugins not setting a path ([#3790](https://togithub.com/evanw/esbuild/issues/3790))
Plugins that return values from `onResolve` without resolving the path (i.e. without setting either `path` or `external: true`) will now cause a warning. This is because esbuild only uses return values from `onResolve` if it successfully resolves the path, and it's not good for invalid input to be silently ignored.
- Add a new Go API for running the CLI with plugins ([#3539](https://togithub.com/evanw/esbuild/pull/3539))
With esbuild's Go API, you can now call `cli.RunWithPlugins(args, plugins)` to pass an array of esbuild plugins to be used during the build process. This allows you to create a CLI that behaves similarly to esbuild's CLI but with additional Go plugins enabled.
This was contributed by [@edewit](https://togithub.com/edewit).
### [`v0.21.5`](https://togithub.com/evanw/esbuild/blob/HEAD/CHANGELOG.md#0215)
[Compare Source](https://togithub.com/evanw/esbuild/compare/v0.21.4...v0.21.5)
- Fix `Symbol.metadata` on classes without a class decorator ([#3781](https://togithub.com/evanw/esbuild/issues/3781))
This release fixes a bug with esbuild's support for the [decorator metadata proposal](https://togithub.com/tc39/proposal-decorator-metadata). Previously esbuild only added the `Symbol.metadata` property to decorated classes if there was a decorator on the class element itself. However, the proposal says that the `Symbol.metadata` property should be present on all classes that have any decorators at all, not just those with a decorator on the class element itself.
- Allow unknown import attributes to be used with the `copy` loader ([#3792](https://togithub.com/evanw/esbuild/issues/3792))
Import attributes (the `with` keyword on `import` statements) are allowed to alter how that path is loaded. For example, esbuild cannot assume that it knows how to load `./bagel.js` as type `bagel`:
```js
// This is an error with "--bundle" without also using "--external:./bagel.js"
import tasty from "./bagel.js" with { type: "bagel" }
```
Because of that, bundling this code with esbuild is an error unless the file `./bagel.js` is external to the bundle (such as with `--bundle --external:./bagel.js`).
However, there is an additional case where it's ok for esbuild to allow this: if the file is loaded using the `copy` loader. That's because the `copy` loader behaves similarly to `--external` in that the file is left external to the bundle. The difference is that the `copy` loader copies the file into the output folder and rewrites the import path while `--external` doesn't. That means the following will now work with the `copy` loader (such as with `--bundle --loader:.bagel=copy`):
```js
// This is no longer an error with "--bundle" and "--loader:.bagel=copy"
import tasty from "./tasty.bagel" with { type: "bagel" }
```
- Support import attributes with glob-style imports ([#3797](https://togithub.com/evanw/esbuild/issues/3797))
This release adds support for import attributes (the `with` option) to glob-style imports (dynamic imports with certain string literal patterns as paths). These imports previously didn't support import attributes due to an oversight. So code like this will now work correctly:
```ts
async function loadLocale(locale: string): Locale {
const data = await import(`./locales/${locale}.data`, { with: { type: 'json' } })
return unpackLocale(locale, data)
}
```
Previously this didn't work even though esbuild normally supports forcing the JSON loader using an import attribute. Attempting to do this used to result in the following error:
✘ [ERROR] No loader is configured for ".data" files: locales/en-US.data
example.ts:2:28:
2 │ const data = await import(`./locales/${locale}.data`, { with: { type: 'json' } })
╵ ~~~~~~~~~~~~~~~~~~~~~~~~~~
In addition, this change means plugins can now access the contents of `with` for glob-style imports.
- Support `${configDir}` in `tsconfig.json` files ([#3782](https://togithub.com/evanw/esbuild/issues/3782))
This adds support for a new feature from the upcoming TypeScript 5.5 release. The character sequence `${configDir}` is now respected at the start of `baseUrl` and `paths` values, which are used by esbuild during bundling to correctly map import paths to file system paths. This feature lets base `tsconfig.json` files specified via `extends` refer to the directory of the top-level `tsconfig.json` file. Here is an example:
```json
{
"compilerOptions": {
"paths": {
"js/*": ["${configDir}/dist/js/*"]
}
}
}
```
You can read more in [TypeScript's blog post about their upcoming 5.5 release](https://devblogs.microsoft.com/typescript/announcing-typescript-5-5-rc/#the-configdir-template-variable-for-configuration-files). Note that this feature does not make use of template literals (you need to use `"${configDir}/dist/js/*"` not `` `${configDir}/dist/js/*` ``). The syntax for `tsconfig.json` is still just JSON with comments, and JSON syntax does not allow template literals. This feature only recognizes `${configDir}` in strings for certain path-like properties, and only at the beginning of the string.
- Fix internal error with `--supported:object-accessors=false` ([#3794](https://togithub.com/evanw/esbuild/issues/3794))
This release fixes a regression in 0.21.0 where some code that was added to esbuild's internal runtime library of helper functions for JavaScript decorators fails to parse when you configure esbuild with `--supported:object-accessors=false`. The reason is that esbuild introduced code that does `{ get [name]() {} }` which uses both the `object-extensions` feature for the `[name]` and the `object-accessors` feature for the `get`, but esbuild was incorrectly only checking for `object-extensions` and not for `object-accessors`. Additional tests have been added to avoid this type of issue in the future. A workaround for this issue in earlier releases is to also add `--supported:object-extensions=false`.
### [`v0.21.4`](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() {}
```
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This PR contains the following updates:
0.20.2->0.23.0Release Notes
evanw/esbuild (esbuild)
### [`v0.23.0`](https://togithub.com/evanw/esbuild/blob/HEAD/CHANGELOG.md#0230) [Compare Source](https://togithub.com/evanw/esbuild/compare/v0.22.0...v0.23.0) ***This release deliberately contains backwards-incompatible changes.*** To avoid automatically picking up releases like this, you should either be pinning the exact version of `esbuild` in your `package.json` file (recommended) or be using a version range syntax that only accepts patch upgrades such as `^0.22.0` or `~0.22.0`. See npm's documentation about [semver](https://docs.npmjs.com/cli/v6/using-npm/semver/) for more information. - Revert the recent change to avoid bundling dependencies for node ([#3819](https://togithub.com/evanw/esbuild/issues/3819)) This release reverts the recent change in version 0.22.0 that made `--packages=external` the default behavior with `--platform=node`. The default is now back to `--packages=bundle`. I've just been made aware that Amazon doesn't pin their dependencies in their "AWS CDK" product, which means that whenever esbuild publishes a new release, many people (potentially everyone?) using their SDK around the world instantly starts using it without Amazon checking that it works first. This change in version 0.22.0 happened to break their SDK. I'm amazed that things haven't broken before this point. This revert attempts to avoid these problems for Amazon's customers. Hopefully Amazon will pin their dependencies in the future. In addition, this is probably a sign that esbuild is used widely enough that it now needs to switch to a more complicated release model. I may have esbuild use a beta channel model for further development. - Fix preserving collapsed JSX whitespace ([#3818](https://togithub.com/evanw/esbuild/issues/3818)) When transformed, certain whitespace inside JSX elements is ignored completely if it collapses to an empty string. However, the whitespace should only be ignored if the JSX is being transformed, not if it's being preserved. This release fixes a bug where esbuild was previously incorrectly ignoring collapsed whitespace with `--jsx=preserve`. Here is an example: ```jsx // Original codeConfiguration
📅 Schedule: Branch creation - At any time (no schedule defined), Automerge - At any time (no schedule defined).
🚦 Automerge: Disabled by config. Please merge this manually once you are satisfied.
♻ Rebasing: Whenever PR becomes conflicted, or you tick the rebase/retry checkbox.
🔕 Ignore: Close this PR and you won't be reminded about this update again.
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