Fork TS Checker Webpack Plugin
Webpack plugin that runs TypeScript type checker on a separate process.
Installation
This plugin requires minimum Node.js 6.11.5, webpack 4, TypeScript 2.1 and optionally ESLint 6 (which itself requires minimum Node.js 8.10.0)
If you depend on webpack 2, webpack 3, or tslint 4, please use older version of the plugin.
# with npm
npm install --save-dev fork-ts-checker-webpack-plugin
# with yarn
yarn add --dev fork-ts-checker-webpack-plugin
Basic webpack config (with ts-loader)
const ForkTsCheckerWebpackPlugin = require('fork-ts-checker-webpack-plugin');
const webpackConfig = {
context: __dirname, // to automatically find tsconfig.json
entry: './src/index.ts',
module: {
rules: [
{
test: /\.tsx?$/,
loader: 'ts-loader',
options: {
// disable type checker - we will use it in fork plugin
transpileOnly: true
}
}
]
},
plugins: [new ForkTsCheckerWebpackPlugin()]
};
Motivation
There was already similar solution - awesome-typescript-loader. You can
add CheckerPlugin
and delegate checker to the separate process. The problem with awesome-typescript-loader
was that, in our case,
it was a lot slower than ts-loader on an incremental build (~20s vs ~3s).
Secondly, we used tslint and we wanted to run this, along with type checker, in a separate process.
This is why this plugin was created. To provide better performance, the plugin reuses Abstract Syntax Trees between compilations and shares
these trees with TSLint.
Modules resolution
It's very important to be aware that this plugin uses TypeScript's, not
webpack's modules resolution. It means that you have to setup tsconfig.json
correctly. For example
if you set files: ['./src/someFile.ts']
in tsconfig.json
, this plugin will check only someFile.ts
for semantic errors. It's because
of performance. The goal of this plugin is to be as fast as possible. With TypeScript's module resolution we don't have to wait for webpack
to compile files (which traverses dependency graph during compilation) - we have a full list of files from the begin.
To debug TypeScript's modules resolution, you can use tsc --traceResolution
command.
ESLint
ESLint is the future of linting in the TypeScript world. If you'd like to use eslint with the plugin, supply this option: eslint: true
and ensure you have the relevant dependencies installed:
yarn add eslint @typescript-eslint/parser @typescript-eslint/eslint-plugin --dev
You should have an ESLint configuration file in your root project directory. Here is a sample .eslintrc.js
configuration for a TypeScript project:
const path = require('path');
module.exports = {
parser: '@typescript-eslint/parser', // Specifies the ESLint parser
extends: [
'plugin:@typescript-eslint/recommended' // Uses the recommended rules from the @typescript-eslint/eslint-plugin
],
parserOptions: {
project: path.resolve(__dirname, './tsconfig.json'),
tsconfigRootDir: __dirname,
ecmaVersion: 2018, // Allows for the parsing of modern ECMAScript features
sourceType: 'module', // Allows for the use of imports
},
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 here.
Options
-
tsconfig
string
: Path to tsconfig.json file. Default:path.resolve(compiler.options.context, './tsconfig.json')
. -
compilerOptions
object
: Allows overriding TypeScript options. Should be specified in the same format as you would do for thecompilerOptions
property in tsconfig.json. Default:{}
. -
eslint
true | undefined
:- If
true
, this activates eslint support.
- If
-
eslintOptions
object
:- Options that can be used to initialise ESLint. See https://eslint.org/docs/developer-guide/nodejs-api#cliengine
-
async
boolean
: True by default -async: false
can block webpack's emit to wait for type checker/linter and to add errors to the webpack's compilation. We recommend to set this tofalse
in projects where type checking is faster than webpack's build - it's better for integration with other plugins. Another scenario where you might want to set this tofalse
is if you use theoverlay
functionality ofwebpack-dev-server
. -
ignoreDiagnostics
number[]
: List of TypeScript diagnostic codes to ignore. -
ignoreLints
string[]
: List of eslint rule names to ignore. -
ignoreLintWarnings
boolean
: If true, will ignore all lint warnings. -
reportFiles
string[]
: Only report errors on files matching these glob patterns. This can be useful when certain types definitions have errors that are not fatal to your application. Default:[]
. Please note that this may behave unexpectedly if using the incremental API as the incremental API doesn't look for global and semantic errors if it has already found syntactic errors.
// in webpack.config.js
new ForkTsCheckerWebpackPlugin({
reportFiles: ['src/**/*.{ts,tsx}', '!src/skip.ts']
});
-
logger
object
: Logger instance. It should be object that implements method:error
,warn
,info
. Default:console
. -
formatter
'default' | 'codeframe' | (issue: Issue) => string)
: Formatter for issues and lints. By default usesdefault
formatter. You can also pass your own formatter as a function (seesrc/issue/
andsrc/formatter/
for API reference). -
formatterOptions
object
: Options passed to formatters (currently onlycodeframe
- see available options) -
silent
boolean
: Iftrue
, logger will not be used. Default:false
. -
checkSyntacticErrors
boolean
: This option is useful if you're using ts-loader inhappyPackMode
with HappyPack or thread-loader to parallelise your builds. Iftrue
it will ensure that the plugin checks for both syntactic errors (egconst array = [{} {}];
) and semantic errors (egconst x: number = '1';
). By default the plugin only checks for semantic errors. This is because when ts-loader is used intranspileOnly
mode, ts-loader will still report syntactic errors. When used inhappyPackMode
it does not. Default:false
. -
memoryLimit
number
: Memory limit for service process in MB. If service exits with allocation failed error, increase this number. Default:2048
. -
vue
boolean | { enabled: boolean, compiler: string }
: Iftrue
orenabled: true
, the linter and compiler will process VueJs single-file-component (.vue) files. See the Vue section further down for information on how to correctly setup your project. -
useTypescriptIncrementalApi
boolean
: If true, the plugin will use incremental compilation API introduced in TypeScript 2.7. Defaults totrue
when working with TypeScript 3+ andfalse
when below 3. The default can be overridden by directly specifying a value. Don't use it together with VueJs enabled - it's not supported yet. -
measureCompilationTime
boolean
: If true, the plugin will measure the time spent inside the compilation code. This may be useful to compare modes, especially if there are other loaders/plugins involved in the compilation. requires Node.js >= 8.5.0 -
typescript
string
: If supplied this is a custom path wheretypescript
can be found. Defaults torequire.resolve('typescript')
. -
resolveModuleNameModule and resolveTypeReferenceDirectiveModule
string
: Both of those options refer to files on the disk that respectively export aresolveModuleName
or aresolveTypeReferenceDirectiveModule
function. These functions will be used to resolve the import statements and the<reference types="...">
directives instead of the default TypeScript implementation. Check the following code for an example of what those functions should look like:Code sample
const { resolveModuleName } = require(`ts-pnp`); exports.resolveModuleName = ( typescript, moduleName, containingFile, compilerOptions, resolutionHost ) => { return resolveModuleName( moduleName, containingFile, compilerOptions, resolutionHost, typescript.resolveModuleName ); }; exports.resolveTypeReferenceDirective = ( typescript, moduleName, containingFile, compilerOptions, resolutionHost ) => { return resolveModuleName( moduleName, containingFile, compilerOptions, resolutionHost, typescript.resolveTypeReferenceDirective ); };
Different behaviour in watch mode
If you turn on webpacks watch mode the fork-ts-checker-notifier-webpack-plugin
will take care of logging type errors, not webpack itself. That means if you set silent: true
you won't see type errors in your console in watch mode.
You can either set silent: false
to show the logging from fork-ts-checker-notifier-webpack-plugin
or set async: false
. Now webpack itself will log type errors again, but note that this can slow down your builds depending on the size of your project.
Notifier
You may already be using the excellent webpack-notifier plugin to make build failures more obvious in the form of system notifications. There's an equivalent notifier plugin designed to work with the fork-ts-checker-webpack-plugin
. It is the fork-ts-checker-notifier-webpack-plugin
and can be found here. This notifier deliberately has a similar API as the webpack-notifier
plugin to make migration easier.
Known Issue Watching Non-Emitting Files
At present there is an issue with the plugin regarding the triggering of type-checking when a change is made in a source file that will not emit js. If you have a file which contains only interface
s and / or type
s then changes to it will not trigger the type checker whilst in watch mode. Sorry about that.
We hope this will be resolved in future; the issue can be tracked here.
Plugin Hooks
This plugin provides some custom webpack hooks (all are sync):
Hook Access Key | Description | Params |
---|---|---|
cancel |
Cancellation has been requested | cancellationToken |
waiting |
Waiting for results | - |
serviceBeforeStart |
Async plugin that can be used for delaying fork-ts-checker-service-start |
- |
serviceStart |
Service will be started | tsconfigPath , memoryLimit |
serviceStartError |
Cannot start service | error |
serviceOutOfMemory |
Service is out of memory | - |
receive |
Plugin receives diagnostics and lints from service | diagnostics , lints |
emit |
Service will add errors and warnings to webpack compilation ('build' mode) | diagnostics , lints , elapsed |
done |
Service finished type checking and webpack finished compilation ('watch' mode) | diagnostics , lints , elapsed |
Accessing plugin hooks
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,
it returns the series of tapable
hooks where you can pass in your callbacks.
// require the plugin
const ForkTsCheckerWebpackPlugin = require('fork-ts-checker-webpack-plugin');
// setup compiler with the plugin
const compiler = webpack({
// .. webpack config
});
// Optionally add the plugin to the compiler
// **Don't do this if already added through configuration**
new ForkTsCheckerWebpackPlugin({
silent: true,
async: true
}).apply(compiler);
// Now get the plugin hooks from compiler
const tsCheckerHooks = ForkTsCheckerWebpackPlugin.getCompilerHooks(compiler);
// These hooks provide access to different events
// =================================================== //
// The properties of tsCheckerHooks corresponds to the //
// Hook Access Key of the table above. //
// =================================================== //
// Example, if we want to run some code when plugin has received diagnostics
// and lint
tsCheckerHooks.receive.tap('yourListenerName', (diagnostics, lint) => {
// do something with diagnostics, perhaps show custom message
console.log(diagnostics);
});
// Say we want to show some message when plugin is waiting for typecheck results
tsCheckerHooks.waiting.tap('yourListenerName', () => {
console.log('waiting for typecheck results');
});
Calling .tap()
on any hooks, requires two arguments.
name
(string
)
The first argument passed to .tap
is the name of your listener callback (yourListenerName
).
It doesn't need to correspond to anything special. It is intended to be used
internally as the name
of
the hook.
callback
(function
)
The second argument is the callback function. Depending on the hook you are tapping into, several arguments are passed to the function. Do check the table above to find out which arguments are passed to which hooks.
Accessing hooks on Webpack Multi-Compiler instance
The above method will not work on webpack multi compiler
instance. The reason is getCompilerHooks
expects (at lease as of now) the same
compiler instance to be passed where the plugin was attached. So in case of
multi compiler, we need to access individual compiler instances.
const ForkTsCheckerWebpackPlugin = require('fork-ts-checker-webpack-plugin');
// setup multi compiler with the plugin
const compiler = webpack([
{
// .. webpack config
},
{
// .. webpack config
}
]);
// safely determine if instance is multi-compiler
if ('compilers' in compiler) {
compiler.compilers.forEach(singleCompiler => {
// get plugin hooks from the single compiler instance
const tsCheckerHooks = ForkTsCheckerWebpackPlugin.getCompilerHooks(
singleCompiler
);
// now access hooks just like before
tsCheckerHooks.waiting.tap('yourListenerName', () => {
console.log('waiting for typecheck results');
});
});
}
Vue
- Turn on the vue option in the plugin in your webpack config:
new ForkTsCheckerWebpackPlugin({
vue: true
});
Optionally change default vue-template-compiler to nativescript-vue-template-compiler if you use nativescript-vue
new ForkTsCheckerWebpackPlugin({
vue: { enabled: true, compiler: 'nativescript-vue-template-compiler' }
});
- To activate TypeScript in your
.vue
files, you need to ensure your script tag's language attribute is set tots
ortsx
(also make sure you include the.vue
extension in all your import statements as shown below):
<script lang="ts">
import Hello from '@/components/hello.vue';
// ...
</script>
- Ideally you are also using
ts-loader
(in transpileOnly mode). Your Webpack config rules may look something like this:
{
test: /\.ts$/,
loader: 'ts-loader',
include: [resolve('src'), resolve('test')],
options: {
appendTsSuffixTo: [/\.vue$/],
transpileOnly: true
}
},
{
test: /\.vue$/,
loader: 'vue-loader',
options: vueLoaderConfig
},
- Ensure your
tsconfig.json
includes .vue files:
// tsconfig.json
{
"include": [
"src/**/*.ts",
"src/**/*.vue"
],
"exclude": [
"node_modules"
]
}
- It accepts any wildcard in your TypeScript configuration:
// tsconfig.json
{
"compilerOptions": {
// ...
"baseUrl": ".",
"paths": {
"@/*": [
"src/*"
],
"~/*": [
"src/*"
]
}
}
}
// In a .ts or .vue file...
import Hello from '@/components/hello.vue'
- If you are working in VSCode, you can get the Vetur extension to complete the developer workflow.
Credits
This plugin was created in Realytics in 2017. Thank you for supporting Open Source.
License
MIT License