# Fork TS Checker Webpack Plugin

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

[![npm version](https://img.shields.io/npm/v/fork-ts-checker-webpack-plugin.svg)](https://www.npmjs.com/package/fork-ts-checker-webpack-plugin) [![build status](https://github.com/TypeStrong/fork-ts-checker-webpack-plugin/workflows/CI/CD/badge.svg?branch=main&event=push)](https://github.com/TypeStrong/fork-ts-checker-webpack-plugin/actions?query=branch%3Amain+event%3Apush) [![downloads](http://img.shields.io/npm/dm/fork-ts-checker-webpack-plugin.svg)](https://npmjs.org/package/fork-ts-checker-webpack-plugin) [![commitizen friendly](https://img.shields.io/badge/commitizen-friendly-brightgreen.svg)](http://commitizen.github.io/cz-cli/) [![code style: prettier](https://img.shields.io/badge/code_style-prettier-ff69b4.svg)](https://github.com/prettier/prettier) [![semantic-release](https://img.shields.io/badge/%20%20%F0%9F%93%A6%F0%9F%9A%80-semantic--release-e10079.svg)](https://github.com/semantic-release/semantic-release)
## Features * Speeds up [TypeScript](https://github.com/Microsoft/TypeScript) type checking and [ESLint](https://eslint.org/) linting (by moving each 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) ✨ * Supports [Vue Single File Component](https://vuejs.org/v2/guide/single-file-components.html) ✅ * Displays nice error messages with the [code frame](https://babeljs.io/docs/en/next/babel-code-frame.html) formatter 🌈 ## Installation This plugin requires minimum **Node.js 10**, **Webpack 4**, **TypeScript 2.7** and optionally **ESLint 6** * If you depend on **Webpack 2**, **Webpack 3**, or **TSLint 4**, please use [version 3](https://github.com/TypeStrong/fork-ts-checker-webpack-plugin/tree/v3.1.1) of the plugin. * If you depend on **TypeScript >= 2.1** and **< 2.7** or you can't update to **Node 10**, please use [version 4](https://github.com/TypeStrong/fork-ts-checker-webpack-plugin/tree/v4.1.4) of the 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', exclude: /node_modules/, options: { // disable type checker - we will use it in fork plugin transpileOnly: true } } ] }, plugins: [new ForkTsCheckerWebpackPlugin()] }; ``` > Examples how to configure it with [babel-loader](https://github.com/babel/babel-loader), [ts-loader](https://github.com/TypeStrong/ts-loader), > [eslint](https://github.com/eslint/eslint) 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. ## ESLint If you'd like to use ESLint with the plugin, ensure you have the relevant dependencies installed: ```sh # with npm npm install --save-dev eslint @typescript-eslint/parser @typescript-eslint/eslint-plugin # with yarn yarn add --dev eslint @typescript-eslint/parser @typescript-eslint/eslint-plugin ``` Then set up ESLint in the plugin. This is the minimal configuration: ```js // webpack.config.js const ForkTsCheckerWebpackPlugin = require('fork-ts-checker-webpack-plugin'); module.exports = { // ...the webpack configuration plugins: [ new ForkTsCheckerWebpackPlugin({ eslint: { files: './src/**/*.{ts,tsx,js,jsx}' // required - same as command `eslint ./src/**/*.{ts,tsx,js,jsx} --ext .ts,.tsx,.js,.jsx` } }) ] }; ``` You should also have an ESLint configuration file in your root project directory. Here is a sample `.eslintrc.js` configuration for a TypeScript project: ```js module.exports = { parser: '@typescript-eslint/parser', parserOptions: { ecmaVersion: 2018, sourceType: 'module', }, extends: [ 'plugin:@typescript-eslint/recommended' ], rules: { // place to specify ESLint rules - can be used to overwrite rules specified from the extended configs // e.g. "@typescript-eslint/explicit-function-return-type": "off", } }; ``` There's a [good explanation on setting up TypeScript ESLint support by Robert Cooper](https://dev.to/robertcoopercode/using-eslint-and-prettier-in-a-typescript-project-53jb). ## 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` or `boolean` | `true` | If a `boolean`, it enables/disables TypeScript checker. If an `object`, see [TypeScript options](#typescript-options). | | `eslint` | `object` | `undefined` | If `undefined`, it disables ESLint linter. If an `object`, see [ESLint options](#eslint-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 object: `{ type: 'codeframe', options: { } }`. | | `logger` | `object` | `{ infrastructure: 'silent', issues: 'console', devServer: true }` | Available loggers are `silent`, `console`, and `webpack-infrastructure`. Infrastructure logger prints additional information, issue logger prints `issues` in the `async` mode. If `devServer` is 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 | | -------------------- | --------- | -------------------------------------------------------------------------------------------------------------- | ----------- | | `enabled` | `boolean` | `true` | If `true`, it enables TypeScript checker. | | `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-tsbuildinfo'` or `'write-dts'` or `'write-references'` | `'write-tsbuildinfo'` | If you use the `babel-loader`, it's recommended to use `write-references` mode to improve initial compilation time. If you use `ts-loader`, it's recommended to use `write-tsbuildinfo` mode to not overwrite files emitted by the `ts-loader`. If you use `ts-loader` with `transpileOnly` flag set to `true`, use `'write-dts` to emit the type definition files. | | `diagnosticOptions` | `object` | `{ syntactic: false, semantic: true, declaration: false, global: false }` | Settings to select which diagnostics do we want to perform. | | `extensions` | `object` | `{}` | See [TypeScript extensions options](#typescript-extensions-options). | | `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. | #### TypeScript extensions options Options for the TypeScript checker extensions (`typescript.extensions` option object). | Name | Type | Default value | Description | | -------------------- | --------------------- | ------------------------- | ----------- | | `vue` | `object` or `boolean` | `false` | If `true`, it enables Vue [Single File Component](https://vuejs.org/v2/guide/single-file-components.html) support. | | `vue.enabled` | `boolean` | `false` | Same as the `vue` option | | `vue.compiler` | `string` | `'vue-template-compiler'` | The package name of the compiler that will be used to parse `.vue` files. You can use `'nativescript-vue-template-compiler'` if you use [nativescript-vue](https://github.com/nativescript-vue/nativescript-vue) | ### ESLint options Options for the ESLint linter (`eslint` option object). | Name | Type | Default value | Description | | -------------------- | ---------------------- | ------------------------- | ----------- | | `enabled` | `boolean` | `false` | If `true`, it enables ESLint linter. If you set the `files` option, it will be `true` by default. | | `files` | `string` or `string[]` | This value is required | One or more [glob patterns](https://en.wikipedia.org/wiki/Glob_(programming)) to the files that should be linted. Works the same as the `eslint` command. | | `memoryLimit` | `number` | `2048` | Memory limit for the linter process in MB. If the process exits with the allocation failed error, try to increase this number. | | `options` | `object` | `{}` | [Options](https://eslint.org/docs/developer-guide/nodejs-api#cliengine) that can be used to initialize ESLint. | ### 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 { origin: 'typescript' | 'eslint'; 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/IssueMatch.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 eslint issues from `.spec.ts` files: ```js module.exports = { // ...the webpack configuration plugins: [ new ForkTsCheckerWebpackPlugin({ issue: { include: [ { file: '**/src/**/*' } ], exclude: [ { origin: 'eslint', file: '**/*.spec.ts' } ] } }) ] }; ```
## Vue.js ⚠️ There are additional **constraints** regarding Vue.js Single File Component support: ⚠️ * It requires **TypeScript >= 3.8.0** (it's a limitation of the `transpileOnly` mode from `ts-loader`) * It doesn't work with the `build` mode (project references) To enable Vue.js support, follow these steps:
Expand Vue.js set up instruction
1. Ensure you have all required packages installed: ```sh # with npm npm install --save vue vue-class-component npm install --save-dev vue-loader ts-loader css-loader vue-template-compiler # with yarn yarn add vue vue-class-component yarn add --dev vue-loader ts-loader css-loader vue-template-compiler ``` 2. Add `tsconfig.json` configuration: ```json { "compilerOptions": { "experimentalDecorators": true, "jsx": "preserve", "target": "ES5", "lib": ["ES6", "DOM"], "baseUrl": ".", "paths": { "@/*": ["src/*"], "~/*": ["src/*"] }, "sourceMap": true, "importsNotUsedAsValues": "preserve" }, "include": [ "src/**/*.ts", "src/**/*.vue" ], "exclude": [ "node_modules" ] } ``` 3. Add `webpack.config.js` configuration: ```js const path = require('path'); const VueLoaderPlugin = require('vue-loader/lib/plugin'); const ForkTsCheckerWebpackPlugin = require('fork-ts-checker-webpack-plugin'); module.exports = { entry: './src/index.ts', output: { filename: 'index.js', path: path.resolve(__dirname, 'dist'), }, module: { rules: [ { test: /\.vue$/, loader: 'vue-loader' }, { test: /\.ts$/, loader: 'ts-loader', exclude: /node_modules/, options: { appendTsSuffixTo: [/\.vue$/], transpileOnly: true } }, { test: /\.css$/, loader: 'css-loader' }, ], }, resolve: { extensions: ['.ts', '.js', '.vue', '.json'], alias: { '@': path.resolve(__dirname, './src'), '~': path.resolve(__dirname, './src'), } }, plugins: [ new VueLoaderPlugin(), new ForkTsCheckerWebpackPlugin({ typescript: { extensions: { vue: true } } }) ] }; ``` 4. Add `src/types/vue.d.ts` file to shim `.vue` modules: ```typescript declare module "*.vue" { import Vue from "vue"; export default Vue; } ``` 5. If you are working in VSCode, you can get the [Vetur](https://marketplace.visualstudio.com/items?itemName=octref.vetur) extension to complete the developer workflow.
## 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() ] }; ``` ## Typings To use the plugin typings, you have to install `@types/webpack`. It's not included by default to not collide with your existing typings (`@types/webpack` imports `@types/node`). [It's an old TypeScript issue](https://github.com/microsoft/TypeScript/issues/18588), the alternative is to set `skipLibCheck: true` in the `compilerOptions` 😉 ```sh # with npm npm install --save-dev @types/webpack # with yarn yarn add --dev @types/webpack ``` ## Profiling types resolution Starting from TypeScript 4.1.0, 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` 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 ## 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