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# Fork TS Checker Webpack Plugin

Webpack plugin that runs TypeScript type checker on a separate process.

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## Features * Speeds up [TypeScript](https://github.com/Microsoft/TypeScript) type checking (by moving it to a separate process) 🏎 * Supports modern TypeScript features like [project references](https://www.typescriptlang.org/docs/handbook/project-references.html) and [incremental mode](https://www.typescriptlang.org/docs/handbook/release-notes/typescript-3-4.html#faster-subsequent-builds-with-the---incremental-flag) ✨ * Displays nice error messages with the [code frame](https://babeljs.io/docs/en/next/babel-code-frame.html) formatter 🌈 ## Installation This plugin requires **Node.js >=12.13.0+**, **Webpack ^5.11.0**, **TypeScript ^3.6.0** * If you depend on **TypeScript 2.1 - 2.6.2**, please use [version 4](https://github.com/TypeStrong/fork-ts-checker-webpack-plugin/tree/v4.1.4) of the plugin. * If you depend on **Webpack 4**, **TypeScript 2.7 - 3.5.3** or **ESLint** feature, please use [version 6](https://github.com/TypeStrong/fork-ts-checker-webpack-plugin/tree/v6.2.6) of the plugin. * If you need Vue.js support, please use [version 6](https://github.com/TypeStrong/fork-ts-checker-webpack-plugin/tree/v6.5.2) of ths plugin ```sh # with npm npm install --save-dev fork-ts-checker-webpack-plugin # with yarn yarn add --dev fork-ts-checker-webpack-plugin ``` The minimal webpack config (with [ts-loader](https://github.com/TypeStrong/ts-loader)) ```js // webpack.config.js const ForkTsCheckerWebpackPlugin = require('fork-ts-checker-webpack-plugin'); module.exports = { context: __dirname, // to automatically find tsconfig.json entry: './src/index.ts', resolve: { extensions: [".ts", ".tsx", ".js"], }, module: { rules: [ { test: /\.tsx?$/, loader: 'ts-loader', // add transpileOnly option if you use ts-loader < 9.3.0 // options: { // transpileOnly: true // } } ] }, plugins: [new ForkTsCheckerWebpackPlugin()], watchOptions: { // for some systems, watching many files can result in a lot of CPU or memory usage // https://webpack.js.org/configuration/watch/#watchoptionsignored // don't use this pattern, if you have a monorepo with linked packages ignored: /node_modules/, }, }; ``` > Examples how to configure it with [babel-loader](https://github.com/babel/babel-loader), [ts-loader](https://github.com/TypeStrong/ts-loader) > and [Visual Studio Code](https://code.visualstudio.com/) are in the [**examples**](./examples) directory. ## Modules resolution It's very important to be aware that **this plugin uses [TypeScript](https://github.com/Microsoft/TypeScript)'s, not [webpack](https://github.com/webpack/webpack)'s modules resolution**. It means that you have to setup `tsconfig.json` correctly. > It's because of the performance - with TypeScript's module resolution we don't have to wait for webpack to compile files. > > To debug TypeScript's modules resolution, you can use `tsc --traceResolution` command. ## Options This plugin uses [`cosmiconfig`](https://github.com/davidtheclark/cosmiconfig). This means that besides the plugin constructor, you can place your configuration in the: * `"fork-ts-checker"` field in the `package.json` * `.fork-ts-checkerrc` file in JSON or YAML format * `fork-ts-checker.config.js` file exporting a JS object Options passed to the plugin constructor will overwrite options from the cosmiconfig (using [deepmerge](https://github.com/TehShrike/deepmerge)). | Name | Type | Default value | Description | |--------------|--------------------------------------|-------------------------------------------|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| | `async` | `boolean` | `compiler.options.mode === 'development'` | If `true`, reports issues **after** webpack's compilation is done. Thanks to that it doesn't block the compilation. Used only in the `watch` mode. | | `typescript` | `object` | `{}` | See [TypeScript options](#typescript-options). | | `issue` | `object` | `{}` | See [Issues options](#issues-options). | | `formatter` | `string` or `object` or `function` | `codeframe` | Available formatters are `basic`, `codeframe` and a custom `function`. To [configure](https://babeljs.io/docs/en/babel-code-frame#options) `codeframe` formatter, pass: `{ type: 'codeframe', options: { } }`. To use absolute file path, pass: `{ type: 'codeframe', pathType: 'absolute' }`. | | `logger` | `{ log: function, error: function }` or `webpack-infrastructure` | `console` | Console-like object to print issues in `async` mode. | | `devServer` | `boolean` | `true` | If set to `false`, errors will not be reported to Webpack Dev Server. | ### TypeScript options Options for the TypeScript checker (`typescript` option object). | Name | Type | Default value | Description | |---------------------|--------------------------------------------------------------------------------|----------------------------------------------------------------------------------------------------------------| | | `memoryLimit` | `number` | `2048` | Memory limit for the checker process in MB. If the process exits with the allocation failed error, try to increase this number. | | `configFile` | `string` | `'tsconfig.json'` | Path to the `tsconfig.json` file (path relative to the `compiler.options.context` or absolute path) | | `configOverwrite` | `object` | `{ compilerOptions: { skipLibCheck: true, sourceMap: false, inlineSourceMap: false, declarationMap: false } }` | This configuration will overwrite configuration from the `tsconfig.json` file. Supported fields are: `extends`, `compilerOptions`, `include`, `exclude`, `files`, and `references`. | | `context` | `string` | `dirname(configuration.configFile)` | The base path for finding files specified in the `tsconfig.json`. Same as the `context` option from the [ts-loader](https://github.com/TypeStrong/ts-loader#context). Useful if you want to keep your `tsconfig.json` in an external package. Keep in mind that **not** having a `tsconfig.json` in your project root can cause different behaviour between `fork-ts-checker-webpack-plugin` and `tsc`. When using editors like `VS Code` it is advised to add a `tsconfig.json` file to the root of the project and extend the config file referenced in option `configFile`. | | `build` | `boolean` | `false` | The equivalent of the `--build` flag for the `tsc` command. | | `mode` | `'readonly'` or `'write-dts'` or `'write-tsbuildinfo'` or `'write-references'` | `build === true ? 'write-tsbuildinfo' ? 'readonly'` | Use `readonly` if you don't want to write anything on the disk, `write-dts` to write only `.d.ts` files, `write-tsbuildinfo` to write only `.tsbuildinfo` files, `write-references` to write both `.js` and `.d.ts` files of project references (last 2 modes requires `build: true`). | | `diagnosticOptions` | `object` | `{ syntactic: false, semantic: true, declaration: false, global: false }` | Settings to select which diagnostics do we want to perform. | | `profile` | `boolean` | `false` | Measures and prints timings related to the TypeScript performance. | | `typescriptPath` | `string` | `require.resolve('typescript')` | If supplied this is a custom path where TypeScript can be found. | ### Issues options Options for the issues filtering (`issue` option object). I could write some plain text explanation of these options but I think code will explain it better: ```typescript interface Issue { severity: 'error' | 'warning'; code: string; file?: string; } type IssueMatch = Partial; // file field supports glob matching type IssuePredicate = (issue: Issue) => boolean; type IssueFilter = IssueMatch | IssuePredicate | (IssueMatch | IssuePredicate)[]; ``` | Name | Type | Default value | Description | |-----------|---------------|---------------|------------------------------------------------------------------------------------------------------------------------------------------------------------| | `include` | `IssueFilter` | `undefined` | If `object`, defines issue properties that should be [matched](src/issue/issue-match.ts). If `function`, acts as a predicate where `issue` is an argument. | | `exclude` | `IssueFilter` | `undefined` | Same as `include` but issues that match this predicate will be excluded. |
Expand example
Include issues from the `src` directory, exclude issues from `.spec.ts` files: ```js module.exports = { // ...the webpack configuration plugins: [ new ForkTsCheckerWebpackPlugin({ issue: { include: [ { file: '**/src/**/*' } ], exclude: [ { file: '**/*.spec.ts' } ] } }) ] }; ```
## Plugin hooks This plugin provides some custom webpack hooks: | Hook key | Type | Params | Description | |------------|----------------------------|-----------------------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------| | `start` | `AsyncSeriesWaterfallHook` | `change, compilation` | Starts issues checking for a compilation. It's an async waterfall hook, so you can modify the list of changed and removed files or delay the start of the service. | | `waiting` | `SyncHook` | `compilation` | Waiting for the issues checking. | | `canceled` | `SyncHook` | `compilation` | Issues checking for the compilation has been canceled. | | `error` | `SyncHook` | `compilation` | An error occurred during issues checking. | | `issues` | `SyncWaterfallHook` | `issues, compilation` | Issues have been received and will be reported. It's a waterfall hook, so you can modify the list of received issues. | To access plugin hooks and tap into the event, we need to use the `getCompilerHooks` static method. When we call this method with a [webpack compiler instance](https://webpack.js.org/api/node/), it returns the object with [tapable](https://github.com/webpack/tapable) hooks where you can pass in your callbacks. ```js // ./src/webpack/MyWebpackPlugin.js const ForkTsCheckerWebpackPlugin = require('fork-ts-checker-webpack-plugin'); class MyWebpackPlugin { apply(compiler) { const hooks = ForkTsCheckerWebpackPlugin.getCompilerHooks(compiler); // log some message on waiting hooks.waiting.tap('MyPlugin', () => { console.log('waiting for issues'); }); // don't show warnings hooks.issues.tap('MyPlugin', (issues) => issues.filter((issue) => issue.severity === 'error') ); } } module.exports = MyWebpackPlugin; // webpack.config.js const ForkTsCheckerWebpackPlugin = require('fork-ts-checker-webpack-plugin'); const MyWebpackPlugin = require('./src/webpack/MyWebpackPlugin'); module.exports = { /* ... */ plugins: [ new ForkTsCheckerWebpackPlugin(), new MyWebpackPlugin() ] }; ``` ## Profiling types resolution When using TypeScript 4.3.0 or newer you can profile long type checks by setting "generateTrace" compiler option. This is an instruction from [microsoft/TypeScript#40063](https://github.com/microsoft/TypeScript/pull/40063): 1. Set "generateTrace": "{folderName}" in your `tsconfig.json` (under `compilerOptions`) 2. Look in the resulting folder. If you used build mode, there will be a `legend.json` telling you what went where. Otherwise, there will be `trace.json` file and `types.json` files. 3. Navigate to [edge://tracing](edge://tracing) or [chrome://tracing](chrome://tracing) and load `trace.json` 4. Expand Process 1 with the little triangle in the left sidebar 5. Click on different blocks to see their payloads in the bottom pane 6. Open `types.json` in an editor 7. When you see a type ID in the tracing output, go-to-line {id} to find data about that type ## Enabling incremental mode You must both set "incremental": true in your `tsconfig.json` (under `compilerOptions`) and also specify mode: 'write-references' in `ForkTsCheckerWebpackPlugin` settings. ## Related projects * [`ts-loader`](https://github.com/TypeStrong/ts-loader) - TypeScript loader for webpack. * [`babel-loader`](https://github.com/babel/babel-loader) - Alternative TypeScript loader for webpack. * [`fork-ts-checker-notifier-webpack-plugin`](https://github.com/johnnyreilly/fork-ts-checker-notifier-webpack-plugin) - Notifies about build status using system notifications (similar to the [webpack-notifier](https://github.com/Turbo87/webpack-notifier)). ## Credits This plugin was created in [Realytics](https://www.realytics.io/) in 2017. Thank you for supporting Open Source. ## License MIT License