TypeScript loader for Webpack

See also:

1. tsdoc.io — TypeScript documentation portal (backed by tygen).

Installation

npm install awesome-typescript-loader --save-dev

Performance issues

Please note that ATL works the same way as a TypeScript compiler as much as possible. So please be careful with your files/exclude/include sections.

ADVICE: Turn on useCache option.

ADVICE: Typically you want your files section to include only entry points.

ADVICE: The loader works faster if you use isolatedModules or forceIsolatedModules options.

ADVICE: The loader works faster if you will use reportFiles to restrict checking scope.

ADVICE: Use the loader together with hard-source-webpack-plugin

The world is changing, other solutions are evolving and ATL may work slower for some workloads. Feel free to try ts-loader with HappyPack or thread-loader and hard-source-webpack-plugin.

Differences between ts-loader

awesome-typescript-loader loader was created mostly to speed-up compilation in my own projects. Some of them are quite big and I wanted to have full control on how my files are compiled. There are two major points:

1) atl has first-class integration with Babel and enables caching possibilities. This can be useful for those who use Typescript with Babel. When useBabel and useCache flags are enabled, typescript's emit will be transpiled with Babel and cached. So next time if source file (+environment) has the same checksum we can totally skip typescript's and babel's transpiling. This significantly reduces build time in this scenario.

2) atl is able to fork type-checker and emitter to a separate process, which also speeds-up some development scenarios (e.g. react with react-hot-loader) So your webpack compilation will end earlier and you can explore compiled version in your browser while your files are typechecked.

Configuration

1. Add .ts as a resolvable extension.
2. Configure all files with a .ts extension to be handled by awesome-typescript-loader.

webpack.config.js

// `CheckerPlugin` is optional. Use it if you want async error reporting.
// We need this plugin to detect a `--watch` mode. It may be removed later
// after https://github.com/webpack/webpack/issues/3460 will be resolved.
const { CheckerPlugin } = require('awesome-typescript-loader')

module.exports = {

  // Currently we need to add '.ts' to the resolve.extensions array.
  resolve: {
    extensions: ['.ts', '.tsx', '.js', '.jsx']
  },

  // Source maps support ('inline-source-map' also works)
  devtool: 'source-map',

  // Add the loader for .ts files.
  module: {
    rules: [
      {
        test: /\.tsx?$/,
        loader: 'awesome-typescript-loader'
      }
    ]
  },
  plugins: [
      new CheckerPlugin()
  ]
};

After that, you will be able to build TypeScript files with webpack.

NodeJS versions

The loader supports NodeJS 4 and newer.

tsconfig.json

You can use the tsconfig.json file to configure your compiler and loader:

{
    "compilerOptions": {
        "noImplicitAny": true,
        "removeComments": true
    },
    "awesomeTypescriptLoaderOptions": {
        /* ... */
    }
}

Supported TypeScript

awesome-typescript-loader@2.x aims to support only typescript@2.x and webpack@2x, if you need old compilers please use 1.x or 0.x versions.

Advanced path resolution in TypeScript 2.0

If you want to use new paths and baseUrl feature of TS 2.0 please include TsConfigPathsPlugin. This feature is available only for webpack@2.1.

const { TsConfigPathsPlugin } = require('awesome-typescript-loader');

resolve: {
    plugins: [
        new TsConfigPathsPlugin(/* { configFileName, compiler } */)
    ]
}

Loader options

silent (boolean) (default=false)

No logging from the checker. Please note that this option disables async error reporting because this option bans console.log() usage.

compiler (string) (default='typescript')

Allows use of TypeScript compilers other than the official one. Must be set to the NPM name of the compiler, e.g. ntypescript or the path to a package folder. Note that the compiler must be installed in your project. You can also use nightly versions.

useTranspileModule (boolean) (default=false)*

Use fast transpileModule emit mode. Disables automatically when you set compilerOption declaration: true (reference).

instance (string) (default='at-loader')

Allows the use of several TypeScript compilers with different settings in one app. Override instance to initialize another instance.

configFileName (string) (default='tsconfig.json')

Specifies the path to a TS config file. This is useful when you have multiple config files. This setting is useless inside a TS config file.

transpileOnly (boolean)

Use this setting to disable type checking, enabling this will nullify the CheckerPlugin usage in your webpack configuration.

errorsAsWarnings (boolean)

Emit all typescript errors as warnings.

forceIsolatedModules (boolean)

Use this setting to disable dependent module recompilation.

ignoreDiagnostics (number[]) (default=[])

You can squelch certain TypeScript errors by specifying an array of diagnostic codes to ignore. For example, you can transpile stage 1 properties from *.js using "ignoreDiagnostics": [8014].

useBabel (boolean) (default=false)

Invoke Babel to transpile files. Useful with ES6 target. Please see useCache option which can improve warm-up time.

If you're using babelOptions, anything in .babelrc will take precedence. This breaks expected usage for scenarios where you need two sets of Babel configs (example: one for Webpack, one for your build tools).

You may want to "babelrc": false to disable .babelrc if you don't want it:

{
    "useBabel": true,
    "babelOptions": {
        "babelrc": false, /* Important line */
        "presets": [
            ["@babel/preset-env", { "targets": "last 2 versions, ie 11", "modules": false }]
        ]
    },
    "babelCore": "@babel/core", // needed for Babel v7
}

babelCore (string) (default=undefined)

Override the path used to find babel-core. Useful if node_modules is installed in a non-standard place or webpack is being invoked from a directory not at the root of the project.

For Babel 7, this should be set to "@babel/core".

babelOptions (object) (default=null)

Use this option to pass some options to Babel (e.g. presets). Please note that .babelrc file is more universal way to do this.

useCache (boolean) (default=false)

Use internal file cache. This is useful with Babel, when processing takes a long time to complete. Improves warm-up time.

usePrecompiledFiles (boolean) (default=false)

Use pre-compiled files if any. Files must be named as {filename}.js and {filename}.map.

cacheDirectory (string) (default='.awcache')

Directory where cache is stored.

reportFiles (string[])

Specify globs to report file diagnostics. ALL OTHER ERRORS WILL NOT BE REPORTED. Example:

reportFiles: [
    "src/**/*.{ts,tsx}"
]

getCustomTransformers (string | ((program: ts.Program) => ts.CustomTransformers | undefined)) (default=undefined)

Provide custom transformers, TypeScript 2.4.1+. Example:

const styledComponentsTransformer = require('typescript-plugin-styled-components').default;
const keysTransformer = require('ts-transformer-keys/transformer').default;

// ...
rules: [
    {
        test: /\.tsx?$/,
        loader: 'awesome-typescript-loader',
        options: {
            // ... other loader's options
            getCustomTransformers: program => ({
                before: [
                    styledComponentsTransformer(),
                    keysTransformer(program)
                ]
            })
        }
    }
]

Compiler options

You can pass compiler options inside the loader query string or in a TS config file.