esbuild-loader
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## π Install ```bash npm i -D esbuild-loader ``` ## π¦ Quick Setup To leverage `esbuild-loader` in your Webpack configuration, add a new rule for `esbuild-loader` matching the files you want to transform, such as `.js`, `.jsx`, `.ts`, or `.tsx`. Make sure to remove any other loaders you were using before (e.g. `babel-loader`/`ts-loader`). Here's an example of how to set it up in your `webpack.config.js`: ```diff module.exports = { module: { rules: [ - // Transpile JavaScript - { - test: /\.js$/, - use: 'babel-loader' - }, - - // Compile TypeScript - { - test: /\.tsx?$/, - use: 'ts-loader' - }, + // Use esbuild to compile JavaScript & TypeScript + { + // Match `.js`, `.jsx`, `.ts` or `.tsx` files + test: /\.[jt]sx?$/, + loader: 'esbuild-loader', + options: { + // JavaScript version to compile to + target: 'es2015' + } + }, // Other rules... ], }, } ``` In this setup, esbuild will automatically determine how to handle each file based on its extension: - `.js` files will be treated as JS (no JSX allowed) - `.jsx` as JSX - `.ts` as TS (no TSX allowed) - `.tsx` as TSX If you want to force a specific loader on different file extensions (e.g. to allow JSX in `.js` files), you can use the [`loader` option](https://github.com/privatenumber/esbuild-loader/#loader): ```diff { test: /\.js$/, loader: 'esbuild-loader', options: { + // Treat `.js` files as `.jsx` files + loader: 'jsx', // JavaScript version to transpile to target: 'es2015' } } ``` ## Loader ### JavaScript `esbuild-loader` can be used in-place of `babel-loader` to transpile new JavaScript syntax into code compatible with older JavaScript engines. While this ensures your code can run smoothly across various environments, note that it can bloat your output code (like Babel). The default target is `esnext`, which means it doesn't perform any transpilations. To specify a target JavaScript engine that only supports ES2015, use the following configuration in your `webpack.config.js`: ```diff { test: /\.jsx?$/, loader: 'esbuild-loader', options: { + target: 'es2015', }, } ``` For a detailed list of supported transpilations and versions, refer to [the esbuild documentation](https://esbuild.github.io/content-types/#javascript). ### TypeScript `esbuild-loader` can be used in-place of `ts-loader` to compile TypeScript. ```json5 { // `.ts` or `.tsx` files test: /\.tsx?$/, loader: 'esbuild-loader', } ``` > [!IMPORTANT] > It's possible to use `loader: 'tsx'` for both `.ts` and `.tsx` files, but this could lead to unexpected behavior as TypeScript and TSX do not have compatible syntaxes. > > [β Read more](https://esbuild.github.io/content-types/#ts-vs-tsx) #### `tsconfig.json` If you have a `tsconfig.json` file in your project, `esbuild-loader` will automatically load it. If it's under a custom name, you can pass in the path via `tsconfig` option: ```diff { test: /\.tsx?$/, loader: 'esbuild-loader', options: { + tsconfig: './tsconfig.custom.json', }, }, ``` > Behind the scenes: [`get-tsconfig`](https://github.com/privatenumber/get-tsconfig) is used to load the tsconfig, and to also resolve the `extends` property if it exists. The `tsconfigRaw` option can be used to pass in a raw `tsconfig` object, but it will not resolve the `extends` property. ##### Caveats - esbuild only supports a subset of `tsconfig` options [(see `TransformOptions` interface)](https://github.com/evanw/esbuild/blob/88821b7e7d46737f633120f91c65f662eace0bcf/lib/shared/types.ts#L159-L165). - Enable [`isolatedModules`](https://www.typescriptlang.org/tsconfig#isolatedModules) to avoid mis-compilation with features like re-exporting types. - Enable [`esModuleInterop`](https://www.typescriptlang.org/tsconfig/#esModuleInterop) to make TypeScript's type system compatible with ESM imports. - Features that require type interpretation, such as `emitDecoratorMetadata` and declaration, are not supported. [β Read more about TypeScript Caveats](https://esbuild.github.io/content-types/#typescript-caveats) #### `tsconfig.json` Paths Use [tsconfig-paths-webpack-plugin](https://github.com/dividab/tsconfig-paths-webpack-plugin) to add support for [`tsconfig.json#paths`](https://www.typescriptlang.org/tsconfig/paths.html). Since `esbuild-loader` only transforms code, it cannot aid Webpack with resolving paths. #### Type-checking esbuild **does not** type check your code. And according to the [esbuild FAQ](https://esbuild.github.io/faq/#:~:text=typescript%20type%20checking%20(just%20run%20tsc%20separately)), it will not be supported. Consider these type-checking alternatives: - Using an IDEs like [VSCode](https://code.visualstudio.com/docs/languages/typescript) or [WebStorm](https://www.jetbrains.com/help/webstorm/typescript-support.html) that has live type-checking built in - Running `tsc --noEmit` to type check - Integrating type-checking to your Webpack build as a separate process using [`fork-ts-checker-webpack-plugin`](https://github.com/TypeStrong/fork-ts-checker-webpack-plugin) ## EsbuildPlugin ### Minification Esbuild supports JavaScript minification, offering a faster alternative to traditional JS minifiers like Terser or UglifyJs. Minification is crucial for reducing file size and improving load times in web development. For a comparative analysis of its performance, refer to these [minification benchmarks](https://github.com/privatenumber/minification-benchmarks). In `webpack.config.js`: ```diff + const { EsbuildPlugin } = require('esbuild-loader') module.exports = { ..., + optimization: { + minimizer: [ + new EsbuildPlugin({ + target: 'es2015' // Syntax to transpile to (see options below for possible values) + }) + ] + }, } ``` > [!TIP] > Utilizing the `target` option allows for the use of newer JavaScript syntax, enhancing minification effectiveness. ### Defining constants Webpack's [`DefinePlugin`](https://webpack.js.org/plugins/define-plugin/) can replaced with `EsbuildPlugin` to define global constants. This could speed up the build by removing the parsing costs associated with the `DefinePlugin`. In `webpack.config.js`: ```diff - const { DefinePlugin } = require('webpack') + const { EsbuildPlugin } = require('esbuild-loader') module.exports = { // ..., plugins:[ - new DefinePlugin({ - 'process.env.NODE_ENV': JSON.stringify(process.env.NODE_ENV), - }) + new EsbuildPlugin({ + define: { + 'process.env.NODE_ENV': JSON.stringify(process.env.NODE_ENV), + }, + }), ] } ``` ### Transpilation If your project does not use TypeScript, JSX, or any other syntax that requires additional configuration beyond what Webpack provides, you can use `EsbuildPlugin` for transpilation instead of the loader. It will be faster because there's fewer files to process, and will produce a smaller output because polyfills will only be added once for the entire build as opposed to per file. To utilize esbuild for transpilation, simply set the `target` option on the plugin to specify which syntax support you want. ## CSS Minification Depending on your setup, there are two ways to minify CSS. You should already have CSS loading setup using [`css-loader`](https://github.com/webpack-contrib/css-loader). ### CSS assets If the CSS is extracted and emitted as `.css` file, you can replace CSS minification plugins like [`css-minimizer-webpack-plugin`](https://github.com/webpack-contrib/css-minimizer-webpack-plugin) with the `EsbuildPlugin`. Assuming the CSS is extracted using something like [MiniCssExtractPlugin](https://github.com/webpack-contrib/mini-css-extract-plugin), in `webpack.config.js`: ```diff const { EsbuildPlugin } = require('esbuild-loader') const MiniCssExtractPlugin = require('mini-css-extract-plugin'); module.exports = { // ..., optimization: { minimizer: [ new EsbuildPlugin({ target: 'es2015', + css: true // Apply minification to CSS assets }) ] }, module: { rules: [ { test: /\.css$/i, use: [ MiniCssExtractPlugin.loader, 'css-loader' ] } ], }, plugins: [ new MiniCssExtractPlugin() ] } ``` ### CSS in JS If your CSS is not emitted as a `.css` file, but rather injected with JavaScript using something like [`style-loader`](https://github.com/webpack-contrib/style-loader), you can use the loader for minification. In `webpack.config.js`: ```diff module.exports = { // ..., module: { rules: [ { test: /\.css$/i, use: [ 'style-loader', 'css-loader', + { + loader: 'esbuild-loader', + options: { + minify: true, + }, + }, ], }, ], }, } ``` ## Bring your own esbuild (Advanced) esbuild-loader comes with a version of esbuild it has been tested to work with. However, [esbuild has a frequent release cadence](https://github.com/evanw/esbuild/releases), and while we try to keep up with the important releases, it can get outdated. To work around this, you can use the `implementation` option in the loader or the plugin to pass in your own version of esbuild (eg. a newer one). > [!WARNING] > β esbuild is not stable yet and can have dramatic differences across releases. Using a different version of esbuild is not guaranteed to work. ```diff + const esbuild = require('esbuild') module.exports = { // ..., module: { rules: [ { test: ..., loader: 'esbuild-loader', options: { // ..., + implementation: esbuild, }, }, ], }, } ``` ## Setup examples If you'd like to see working Webpack builds that use esbuild-loader for basic JS, React, TypeScript, Next.js, etc. check out the examples repo: [β esbuild-loader examples](https://github.com/privatenumber/esbuild-loader-examples) ## βοΈ Options ### Loader The loader supports [all Transform options from esbuild](https://github.com/evanw/esbuild/blob/88821b7e7d46737f633120f91c65f662eace0bcf/lib/shared/types.ts#L158-L172). Note: - Source-maps are automatically configured for you via [`devtool`](https://webpack.js.org/configuration/devtool/). `sourcemap`/`sourcefile` options are ignored. - The root `tsconfig.json` is automatically detected for you. You don't need to pass in [`tsconfigRaw`](https://esbuild.github.io/api/#tsconfig-raw) unless it's in a different path. Here are some common configurations and custom options: #### tsconfig Type: `string` Pass in the file path to a **custom** tsconfig file. If the file name is `tsconfig.json`, it will automatically detect it. #### target Type: `string | Array
