webpack accepts configuration files written in multiple programming and data languages. The list of supported file extensions can be found at the node-interpret package. Using node-interpret, webpack can handle many different types of configuration files.

TypeScript

To write the webpack configuration in TypeScript, you would first install the necessary dependencies, i.e., TypeScript and the relevant type definitions from the DefinitelyTyped project:

npm install --save-dev typescript ts-node @types/node @types/webpack
# and, if using webpack-dev-server
npm install --save-dev @types/webpack-dev-server

and then proceed to write your configuration:

webpack.config.ts

import path from 'path';
import webpack from 'webpack';

const config: webpack.Configuration = {
  mode: 'production',
  entry: './foo.js',
  output: {
    path: path.resolve(__dirname, 'dist'),
    filename: 'foo.bundle.js'
  }
};

export default config;

Above sample assumes version >= 2.7 or newer of TypeScript is used with the new esModuleInterop and allowSyntheticDefaultImports compiler options in your tsconfig.json file.

Note that you'll also need to check your tsconfig.json file. If the module in compilerOptions in tsconfig.json is commonjs, the setting is complete, else webpack will fail with an error. This occurs because ts-node does not support any module syntax other than commonjs.

There are two solutions to this issue:

• Modify tsconfig.json.
• Install tsconfig-paths.

The first option is to open your tsconfig.json file and look for compilerOptions. Set target to "ES5" and module to "CommonJS" (or completely remove the module option).

The second option is to install the tsconfig-paths package:

npm install --save-dev tsconfig-paths

And create a separate TypeScript configuration specifically for your webpack configs:

tsconfig-for-webpack-config.json

{
  "compilerOptions": {
    "module": "commonjs",
    "target": "es5",
    "esModuleInterop": true
  }
}

ts-node can resolve a tsconfig.json file using the environment variable provided by tsconfig-paths.

Then set the environment variable process.env.TS_NODE_PROJECT provided by tsconfig-paths like so:

package.json

{
  "scripts": {
    "build": "cross-env TS_NODE_PROJECT=\"tsconfig-for-webpack-config.json\" webpack"
  }
}

We had been getting reports that TS_NODE_PROJECT might not work with "TS_NODE_PROJECT" unrecognized command error. Therefore running it with cross-env seems to fix the issue, for more info see this issue.

CoffeeScript

Similarly, to use CoffeeScript, you would first install the necessary dependencies:

npm install --save-dev coffee-script

and then proceed to write your configuration:

webpack.config.coffee

HtmlWebpackPlugin = require('html-webpack-plugin')
webpack = require('webpack')
path = require('path')

config =
  mode: 'production'
  entry: './path/to/my/entry/file.js'
  output:
    path: path.resolve(__dirname, 'dist')
    filename: 'my-first-webpack.bundle.js'
  module: rules: [ {
    test: /\.(js|jsx)$/
    use: 'babel-loader'
  } ]
  plugins: [
    new HtmlWebpackPlugin(template: './src/index.html')
  ]

module.exports = config

Babel and JSX

In the example below JSX (React JavaScript Markup) and Babel are used to create a JSON Configuration that webpack can understand.

Courtesy of Jason Miller

First install the necessary dependencies:

npm install --save-dev babel-register jsxobj babel-preset-es2015

.babelrc

{
  "presets": [ "es2015" ]
}

webpack.config.babel.js

import jsxobj from 'jsxobj';

// example of an imported plugin
const CustomPlugin = config => ({
  ...config,
  name: 'custom-plugin'
});

export default (
  <webpack target="web" watch mode="production">
    <entry path="src/index.js" />
    <resolve>
      <alias {...{
        react: 'preact-compat',
        'react-dom': 'preact-compat'
      }} />
    </resolve>
    <plugins>
      <CustomPlugin foo="bar" />
    </plugins>
  </webpack>
);

If you are using Babel elsewhere and have modules set to false, you will have to either maintain two separate .babelrc files or use const jsxobj = require('jsxobj'); and module.exports instead of the new import and export syntax. This is because while Node does support many new ES6 features, they don't yet support ES6 module syntax.