This is the typescript loader for webpack.
We have a number of example setups to accomodate different workflows. From "vanilla" ts-loader, to using ts-loader in combination with babel for transpilation, happypack or thread-loader for faster builds and fork-ts-checker-webpack-plugin for performing type checking in a separate process. Not forgetting Hot Module Replacement. Our examples can be found here.
ts-loader works very well in combination with babel and babel-loader. There is an example of this in the official TypeScript Samples. Alternatively take a look at our own example.
As your project becomes bigger and bigger, compilation time increases linearly. It's because typescript's semantic checker has to inspect all files on every rebuild. The simple solution is to disable it by using the transpileOnly: true option, but doing so leaves you without type checking.
You probably don't want to give up type checking; that's rather the point of TypeScript. So what you can do is use the fork-ts-checker-webpack-plugin. It runs the type checker on a separate process, so your build remains fast thanks to transpileOnly: true but you still have the type checking. Also, the plugin has several optimizations to make incremental type checking faster (AST cache, multiple workers).
If you'd like to see a simple setup take a look at our simple example. For a more complex setup take a look at our more involved example.
If you'd like to make things even faster still (I know, right?) then you might want to consider using ts-loader with happypack which speeds builds by parallelising work. (This should be used in combination with fork-ts-checker-webpack-plugin for typechecking.) If you'd like to see a simple setup take a look at our simple example. For a more complex setup take a look at our more involved example.
There is a "webpack-way" of parallelising builds. Instead of using happypack you can use ts-loader with ts-loader with thread-loader and cache-loader in combination. (Again, this should be used in combination with fork-ts-checker-webpack-plugin for typechecking.) If you'd like to see a simple setup take a look at our simple example. For a more complex setup take a look at our more involved example.
To read more on this look at this webpack Medium post.
yarn add ts-loader
or
npm install ts-loader
You will also need to install TypeScript if you have not already.
yarn add typescript
or
npm install typescript
Use webpack like normal, including webpack --watch and webpack-dev-server, or through another
build system using the Node.js API.
- TypeScript: 2.4.1+
- webpack: 4.x+ (please use ts-loader 3.x if you need webpack 2 or 3 support)
- node: 6.11.5 minimum (aligned with webpack 4)
A full test suite runs each night (and on each pull request). It runs both on Linux and Windows, testing ts-loader against major releases of TypeScript. The test suite also runs against TypeScript@next (because we want to use it as much as you do).
If you become aware of issues not caught by the test suite then please let us know. Better yet, write a test and submit it in a PR!
-
Create or update
webpack.config.jslike so:module.exports = { mode: 'development', devtool: 'inline-source-map', entry: './app.ts', output: { filename: 'bundle.js' }, resolve: { // Add `.ts` and `.tsx` as a resolvable extension. extensions: ['.ts', '.tsx', '.js'] }, module: { rules: [ // all files with a `.ts` or `.tsx` extension will be handled by `ts-loader` { test: /\.tsx?$/, loader: 'ts-loader' } ] } }
-
Add a
tsconfig.jsonfile. (The one below is super simple; but you can tweak this to your hearts desire){ "compilerOptions": { "sourceMap": true } }
The tsconfig.json file controls
TypeScript-related options so that your IDE, the tsc command, and this loader all share the
same options.
If you want to be able to debug your original source then you can thanks to the magic of sourcemaps. There are 2 steps to getting this set up with ts-loader and webpack.
First, for ts-loader to produce sourcemaps, you will need to set the tsconfig.json option as "sourceMap": true.
Second, you need to set the devtool option in your webpack.config.js to support the type of sourcemaps you want. To make your choice have a read of the devtool webpack docs. You may be somewhat daunted by the choice available. You may also want to vary the sourcemap strategy depending on your build environment. Here are some example strategies for different environments:
devtool: 'inline-source-map'- Solid sourcemap support; the best "all-rounder". Works well with karma-webpack (not all strategies do)devtool: 'cheap-module-eval-source-map'- Best support for sourcemaps whilst debugging.devtool: 'source-map'- Approach that plays well with UglifyJsPlugin; typically you might use this in Production
Loading css and other resources is possible but you will need to make sure that
you have defined the require function in a declaration file.
declare var require: {
<T>(path: string): T;
(paths: string[], callback: (...modules: any[]) => void): void;
ensure: (paths: string[], callback: (require: <T>(path: string) => T) => void) => void;
};Then you can simply require assets or chunks per the webpack documentation.
require('!style!css!./style.css');The same basic process is required for code splitting. In this case, you import modules you need but you
don't directly use them. Instead you require them at split points. See this example and this example for more details.
TypeScript 2.4 provides support for ECMAScript's new import() calls. These calls import a module and return a promise to that module. This is also supported in webpack - details on usage can be found here. Happy code splitting!
To output a built .d.ts file, you can set "declaration": true in your tsconfig, and use the DeclarationBundlerPlugin in your webpack config.
The build should fail on TypeScript compilation errors as of webpack 2. If for some reason it does not, you can use the webpack-fail-plugin.
For more background have a read of this issue.
If you want to resolve modules according to baseUrl and paths in your tsconfig.json then you can use the tsconfig-paths-webpack-plugin package. For details about this functionality, see the module resolution documentation.
This feature requires webpack 2.1+ and TypeScript 2.0+. Use the config below or check the package for more information on usage.
const TsconfigPathsPlugin = require('tsconfig-paths-webpack-plugin');
module.exports = {
...
resolve: {
plugins: [new TsconfigPathsPlugin({ /*configFile: "./path/to/tsconfig.json" */ })]
}
...
}There are two types of options: TypeScript options (aka "compiler options") and loader options. TypeScript options should be set using a tsconfig.json file. Loader options can be specified through the options property in the webpack configuration:
module.exports = {
...
module: {
rules: [
{
test: /\.tsx?$/,
use: [
{
loader: 'ts-loader',
options: {
transpileOnly: true
}
}
]
}
]
}
}If you want to speed up compilation significantly you can set this flag. However, many of the benefits you get from static type checking between different dependencies in your application will be lost.
It's advisable to use transpileOnly alongside the fork-ts-checker-webpack-plugin to get full type checking again. To see what this looks like in practice then either take a look at our simple example. For a more complex setup take a look at our more involved example.
If you're using HappyPack or thread-loader to parallise your builds then you'll need to set this to true. This implicitly sets *transpileOnly* to true and WARNING! stops registering all errors to webpack.
It's advisable to use this with the fork-ts-checker-webpack-plugin to get full type checking again. To see what this looks like in practice then either take a look at our simple HappyPack example / our simple thread-loader example. For a more complex setup take a look at our more involved HappyPack example / more involved thread-loader example. IMPORTANT: If you are using fork-ts-checker-webpack-plugin alongside HappyPack or thread-loader then ensure you set the checkSyntacticErrors option like so:
new ForkTsCheckerWebpackPlugin({ checkSyntacticErrors: true })
This will ensure that the plugin checks for both syntactic errors (eg const array = [{} {}];) and semantic errors (eg const x: number = '1';). By default the plugin only checks for semantic errors (as when used with ts-loader in transpileOnly mode, ts-loader will still report syntactic errors).
Provide custom transformers - only compatible with TypeScript 2.3+ (and 2.4 if using transpileOnly mode). For example usage take a look at typescript-plugin-styled-components or our test.
This is important if you read from stdout or stderr and for proper error handling. The default value ensures that you can read from stdout e.g. via pipes or you use webpack -j to generate json output.
Can be info, warn or error which limits the log output to the specified log level.
Beware of the fact that errors are written to stderr and everything else is written to stderr (or stdout if logInfoToStdOut is true).
If true, no console.log messages will be emitted. Note that most error messages are emitted via webpack which is not affected by this flag.
You can squelch certain TypeScript errors by specifying an array of diagnostic codes to ignore.
Only report errors on files matching these glob patterns.
// in webpack.config.js
{
test: /\.ts$/,
loader: 'ts-loader',
options: { reportFiles: ['src/**/*.{ts,tsx}', '!src/skip.ts'] }
}This can be useful when certain types definitions have errors that are not fatal to your application.
Allows use of TypeScript compilers other than the official one. Should be
set to the NPM name of the compiler, eg ntypescript.
Allows you to specify where to find the TypeScript configuration file.
You may provide
- just a file name. The loader then will search for the config file of each entry point in the respective entry point's containing folder. If a config file cannot be found there, it will travel up the parent directory chain and look for the config file in those folders.
- a relative path to the configuration file. It will be resolved relative to the respective
.tsentry file. - an absolute path to the configuration file.
If false, disables built-in colors in logger messages.
By default ts-loader formats TypeScript compiler output for an error or a warning in the style:
[tsl] ERROR in myFile.ts(3,14)
TS4711: you did something very wrong
If that format is not to your taste you can supply your own formatter using the errorFormatter option. Below is a template for a custom error formatter. Please note that the colors parameter is an instance of chalk which you can use to color your output. (This instance will respect the colors option.)
function customErrorFormatter(error, colors) {
const messageColor = error.severity === 'warning' ? colors.bold.yellow : colors.bold.red;
return 'Does not compute.... ' + messageColor(Object.keys(error).map(key => `${key}: ${error[key]}`));
}If the above formatter received an error like this:
{
"code":2307,
"severity": "error",
"content": "Cannot find module 'components/myComponent2'.",
"file":"/.test/errorFormatter/app.ts",
"line":2,
"character":31
}
It would produce an error message that said:
Does not compute.... code: 2307,severity: error,content: Cannot find module 'components/myComponent2'.,file: /.test/errorFormatter/app.ts,line: 2,character: 31
And the bit after "Does not compute.... " would be red.
Allows overriding TypeScript options. Should be specified in the same format
as you would do for the compilerOptions property in tsconfig.json.
Advanced option to force files to go through different instances of the TypeScript compiler. Can be used to force segregation between different parts of your code.
A list of regular expressions to be matched against filename. If filename matches one of the regular expressions, a .ts or .tsx suffix will be appended to that filename.
This is useful for *.vue file format for now. (Probably will benefit from the new single file format in the future.)
Example:
webpack.config.js:
module.exports = {
entry: './index.vue',
output: { filename: 'bundle.js' },
resolve: {
extensions: ['.ts', '.vue']
},
module: {
rules: [
{ test: /\.vue$/, loader: 'vue-loader' },
{ test: /\.ts$/, loader: 'ts-loader', options: { appendTsSuffixTo: [/\.vue$/] } }
]
}
}index.vue
<template><p>hello {{msg}}</p></template>
<script lang="ts">
export default {
data(): Object {
return {
msg: "world"
}
},
}
</script>We can handle .tsx by quite similar way:
webpack.config.js:
module.exports = {
entry: './index.vue',
output: { filename: 'bundle.js' },
resolve: {
extensions: ['.ts', '.tsx', '.vue', '.vuex']
},
module: {
rules: [
{ test: /\.vue$/, loader: 'vue-loader',
options: {
loaders: {
ts: 'ts-loader',
tsx: 'babel-loader!ts-loader',
}
}
},
{ test: /\.ts$/, loader: 'ts-loader', options: { appendTsSuffixTo: [/TS\.vue$/] } }
{ test: /\.tsx$/, loader: 'babel-loader!ts-loader', options: { appendTsxSuffixTo: [/TSX\.vue$/] } }
]
}
}tsconfig.json (set jsx option to preserve to let babel handle jsx)
{
"compilerOptions": {
"jsx": "preserve"
}
}index.vue
<script lang="tsx">
export default {
functional: true,
render(h, c) {
return (<div>Content</div>);
}
}
</script>Or if you want to use only tsx, just use the appendTsxSuffixTo option only:
{ test: /\.ts$/, loader: 'ts-loader' }
{ test: /\.tsx$/, loader: 'babel-loader!ts-loader', options: { appendTsxSuffixTo: [/\.vue$/] } }The default behavior of ts-loader is to act as a drop-in replacement for the tsc command,
so it respects the include, files, and exclude options in your tsconfig.json, loading
any files specified by those options. The onlyCompileBundledFiles option modifies this behavior,
loading only those files that are actually bundled by webpack, as well as any .d.ts files included
by the tsconfig.json settings. .d.ts files are still included because they may be needed for
compilation without being explicitly imported, and therefore not picked up by webpack.
If set, will parse the TypeScript configuration file with given absolute path as base path.
Per default the directory of the configuration file is used as base path. Relative paths in the configuration
file are resolved with respect to the base path when parsed. Option context allows to set option
configFile to a path other than the project root (e.g. a NPM package), while the base path for ts-loader
can remain the project root.
Keep in mind that not having a tsconfig.json in your project root can cause different behaviour between ts-loader 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. For more information please read the PR that
is the base and read the PR that contributed this option.
Webpack:
{
loader: require.resolve('ts-loader'),
options: {
context: __dirname,
configFile: require.resolve('ts-config-react-app')
}
}Extending tsconfig.json:
{ "extends": "./node_modules/ts-config-react-app/index" }Note that changes in the extending file while not be respected by ts-loader. Its purpose is to satisfy the code editor.
There's a known "gotcha" if you are using webpack 2 with the LoaderOptionsPlugin. If you are faced with the Cannot read property 'unsafeCache' of undefined error then you probably need to supply a resolve object as below: (Thanks @jeffijoe!)
new LoaderOptionsPlugin({
debug: false,
options: {
resolve: {
extensions: ['.ts', '.tsx', '.js']
}
}
}) Because TS will generate .js and .d.ts files, you should ignore these files, otherwise watchers may go into an infinite watch loop. For example, when using Webpack, you may wish to add this to your webpack.conf.js file:
plugins: [
new webpack.WatchIgnorePlugin([
/\.js$/,
/\.d\.ts$/
])
],It's worth noting that use of the LoaderOptionsPlugin is only supposed to be a stopgap measure. You may want to look at removing it entirely.
This is your TypeScript loader! We want you to help make it even better. Please feel free to contribute; see the contributor's guide to get started.
MIT License