How can I use ES6 in webpack.config.js?

Question

How to use ES6 in webpack.config ? Like this repo https://github.com/kriasoft/react-starter-kit does ?

For instance:

using this

import webpack from 'webpack';

instead of

var webpack = require('webpack');

It is quite a curiosity rather than a need.

Answer 1

Try naming your config as webpack.config.babel.js. You should have babel-register included in the project. Example at react-router-bootstrap.

Webpack relies on interpret internally to make this work.

Answer 2

As an alternative to what @bebraw suggests, you can create a JavaScript automation script with ES6+ syntax:

// tools/bundle.js

import webpack from 'webpack';
import webpackConfig from './webpack.config.js'; // <-- Contains ES6+

const bundler = webpack(webpackConfig);

bundler.run(...);

And execute it with babel:

$ babel-node tools/bundle

P.S.: Calling webpack via JavaScript API might be a better approach (than by calling it via a command line) when you need to implement more complex build steps. E.g. after server-side bundle is ready, startup Node.js app server, and right after Node.js server is started, launch BrowserSync dev server.

See also:

• React Starter Kit (package.json/scripts, tools/bundle.js, tools/webpack.config.js)
• React Static Boilerplate (run.js, webpack.config.js, node run)
• You might not need Gulp.js

Answer 3

Another approach is to have a npm script like this: "webpack": "babel-node ./node_modules/webpack/bin/webpack", and run it like so: npm run webpack.

Answer 4

This is what worked for me using webpack 4:

In package.json:

"scripts": {
    "dev": "cross-env APP_ENV=dev webpack-serve --require @babel/register"
},

"devDependencies": {
    "@babel/core": "^7.0.0-rc.1",
    "@babel/register": "^7.0.0-rc.1",
    "@babel/preset-env": "^7.0.0-rc.1",
    "babel-plugin-transform-es2015-modules-commonjs": "^6.26.2"
},

"babel": {
  "presets": [
    ["@babel/preset-env", {
      "targets": {
        "node": "current"
      }
    }]
  ],
  "plugins": [
    "transform-es2015-modules-commonjs"
  ]
}

You can clearly see how each dependency is used, so no surprises there.

Note I am using webpack-serve--require, but if you want to use the webpack command instead, replace it with webpack --config-register. In either case, @babel/register is needed to make this work.

And that's it!

yarn dev

And you are able to use es6 in the config!

---

For webpack-dev-server, use the --config-register option which is the same as with the webpack command

---

NOTE:

NO need to rename the config file to webpack.config.babel.js (as suggested by the accepted answer). webpack.config.js will work just fine.

Answer 5

I had a problem getting @Juho's solution running with Webpack 2. The Webpack migration docs suggest you to turn of babel module parsing:

It is important to note that you will want to tell Babel to not parse these module symbols so webpack can use them. You can do this by setting the following in your .babelrc or babel-loader options.

.babelrc:

{
    "presets": [
         ["es2015", { "modules": false }]
    ]
}

Sadly, this conflicts with the automatic babel register functionality. Removing

{ "modules": false }

from the babel config got things running again. However, this would result in breaking tree-shaking, so a complete solution would involve overwriting the presets in the loader options:

module: {
    rules: [
        {
            test: /\.js$/,
            include: path.resolve('src'),
            loader: 'babel-loader',
            options: {
                babelrc: false,
                presets: [['env', {modules: false}]]
            }
        }
    ]
}

---

Edit, 13th Nov 2017; updated webpack config snippet to Webpack 3 (thanks to @x-yuri). Old, Webpack 2 snippet:

{
    test: /\.js$/,
    exclude: ['node_modules'],
    loader: 'babel',
    query: {
        babelrc: false,
        presets: [
            ['es2015', { modules: false }],
        ],
    },
},

Answer 6

For readers in 2022:

"webpack": "^5.70.0",
"webpack-cli": "^4.9.2",
"webpack-dev-server": "^4.7.4"

1. Add "type": "module" in package.json

2. Change the syntax of your webpack.config.js to ESM.

3. Enjoy.

Answer 7

This is really easy, but it wasn't obvious to me from any of the answers, so if anyone else is confused like me:

Just append .babel to the part of your filename before the extension (assuming that you have babel-register installed as a dependency).

Example:

mv webpack.config.js webpack.config.babel.js

Answer 8

Configuration for Babel 7 & Webpack 4

package.json

    ...
    "scripts": {
        "start": "webpack-dev-server --env.dev",
        "build": "webpack --env.prod",
    },
    "keywords": [],
    "author": "",
    "license": "ISC",
    "devDependencies": {
        "@babel/core": "^7.0.0",
        "@babel/plugin-proposal-class-properties": "^7.0.0",
        "@babel/preset-env": "^7.0.0",
        "@babel/preset-react": "^7.0.0",
        "@babel/register": "^7.0.0",
        "babel-loader": "^8.0.0",
        ...
        "webpack": "^4.17.2",
        "webpack-cli": "^3.1.0",
        "webpack-config-utils": "^2.3.1",
        "webpack-dev-server": "^3.1.8"

.babelrc

{
    "presets": ["@babel/preset-env", "@babel/preset-react"],
    "plugins": ["@babel/plugin-proposal-class-properties"]
}

webpack.config.babel.js

import webpack from 'webpack';
import { resolve } from 'path';

import { getIfUtils, removeEmpty } from 'webpack-config-utils';

export default env => {
    const { ifProd, ifNotProd } = getIfUtils(env);

    return {
        mode: ifProd('production', 'development'),
        devtool: ifNotProd('cheap-module-source-map'),
        output: {
            path: resolve(__dirname, ifProd('prod', 'dev')),
            filename: 'bundle.js'
        },

Answer 9

For TypeScript: straight from https://webpack.js.org/configuration/configuration-languages/

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

then proceed to write your, e.g.: 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;

Check the link for more details where you can use a plugin to have a separate tsconfig file just for the webpack config if you're not targeting commonjs (which is a req for this to work since it relies on ts-node).

Answer 10

One more way is to use require argument for node:

node -r babel-register ./node_modules/webpack/bin/webpack

Found this way in electron-react-boilerplate, look at build-main and build-renderer scripts.

Answer 11

Rename webpack.config.js to webpack.config.babel.js.

Then in .babelrc: {"presets": ["es2015"]}

However, if you want to use a different babel config for babel-cli, your .babelrc might look something like this:

{
  "env": {
    "babel-cli": {
      "presets": [["es2015", {"modules": false}]]
    },
    "production": {
      "presets": ["es2015"]
    },
    "development": {
      "presets": ["es2015"]
    }
  }
}

And in package.json:

{
  "scripts": {
    "babel": "BABEL_ENV='babel-cli' babel src -d dist/babel --source-maps",
    "build-dev": "NODE_ENV='development' webpack -d --progress --profile --colors",
    ...
  },
  ...
}

It's dumb but the {"modules": false} will break webpack if you don't use different envs.

For more info about .babelrc, check the official docs.

Answer 12

Don't have enough rep to comment, but I wanted to add for any TypeScript users out there a similar solution to @Sandrik above

I have two scripts that I use pointing to webpack configs (JS files) that contain ES6 syntax.

"start-dev": "./node_modules/.bin/ts-node ./node_modules/webpack-dev-server/bin/webpack-dev-server.js --config ./webpack/webpack.config.dev.js"

and

"build": "./node_modules/.bin/ts-node ./node_modules/webpack/bin/webpack.js --config webpack/webpack.config.js"

Answer 13

Using Webpack 4 and Babel 7

To setup a webpack configuration file to use ES2015 requires Babel:

Install dev dependencies:

npm i -D  webpack \
          webpack-cli \
          webpack-dev-server \
          @babel/core \
          @babel/register \
          @babel/preset-env
npm i -D  html-webpack-plugin

Create a .babelrc file:

{
  "presets": ["@babel/preset-env"]
}

Create your webpack config, webpack.config.babel.js:

import { resolve as _resolve } from 'path';
import HtmlWebpackPlugin from 'html-webpack-plugin';

const config = {
  mode: 'development',
  devServer: {
    contentBase: './dist'
  },
  plugins: [
    new HtmlWebpackPlugin({
      filename: 'index.html',
      template: 'src/index.html'
    })
  ],
  resolve: {
    modules: [_resolve(__dirname, './src'), 'node_modules']
  }
};

export default config;

Create your scripts in package.json:

  "scripts": {
    "test": "echo \"Error: no test specified\" && exit 1",
    "build": "webpack",
    "start": "webpack-dev-server --open"
  },

Run npm run build and npm start.

The webpack config is based on a sample project with the following directory structure:

├── README.md
├── package-lock.json
├── package.json
├── src
│   ├── Greeter.js
│   ├── index.html
│   └── index.js
└── webpack.config.babel.js

Sample project: Webpack Configuration Language Using Babel

Answer 14

My Best approach along with npm script is

node -r babel-register ./node_modules/webpack/bin/webpack

and configure rest of scripts as per your requirement for Babel

Answer 15

After tons of the documents...

1. Just install es2015 preset (not env !!!) and add it to

   .babelrc:
   {
       "presets": [
            ["es2015", { "modules": false }]
       ]
   }
   

2. Rename your webpack.config.js to webpack.config.babel.js

Answer 16

Adding es6 to webpack is a 3 step process

1. In webpack.config.js add

   module:{
   
             rules:[
               {
                 test: /\.js$/,
                 loader: 'babel-loader'
               }
             ]
          }
   

   2. Create a .babel.rc and add inside it

{
    "presets": ["@babel/env", "@babel/react"],
    "plugins": [
        [
          "@babel/plugin-proposal-class-properties",
        ]
      ]
}

3. in package.json add

npm install @babel/core --save-dev
npm install @babel/preset-env --save-dev
npm install @babel/preset-react --save-dev
npm install @babel/plugin-proposal-class-properties --save-dev
npm install babel-loader --save-dev

Answer 17

Ran into this issue, resolved it by installing lastest webpack, webpack-cli and webpack-devserver see example here

Answer 18

Edit: Works as of Feb 2021

https://github.com/webpack/webpack-cli/pull/2381

---

You can't. You have to convert it to CommonJS, either with babel or esm.

https://github.com/webpack/webpack-cli/issues/282

But you can run webpack -r esm @babel/register