webpack.config.js

const path = require('path')
const webpack = require('webpack')
const ExtractTextPlugin = require('extract-text-webpack-plugin')
const HtmlWebpackPlugin = require('html-webpack-plugin')
const CopyWebpackPlugin = require('copy-webpack-plugin')

const env = process.env.NODE_ENV == 'production' ? 'production' : '';

const GLOBALS = {
  'process.env.NODE_ENV': JSON.stringify(env)
};

module.exports = {
  // Entry files for our popup and background pages
  entry: {
    popup: './src/js/popup.js',
    script: './src/js/script.js',
    background: './src/js/background.js'
  },
  // Extension will be built into ./dist folder, which we can then load as unpacked extension in Chrome
  output: {
    path: path.resolve(__dirname, 'dist'),
    filename: '[name].bundle.js'
  },
  // Here we define loaders for different file types
  module: {
    rules: [
      // We use Babel to transpile JSX
      {
        test: /\.js$/,
        include: [
          path.resolve(__dirname, './src')
        ],
        exclude: /node_modules/,
        loader: 'babel-loader',
        query: {
          presets: ['es2015']
        }
      },
      {
        test: /\.css$/,
        loader: ExtractTextPlugin.extract({
          fallback: 'style-loader',
          use: 'css-loader'
        })
      },
      {
        test: /\.(ico|eot|otf|webp|ttf|woff|woff2)(\?.*)?$/,
        use: 'file-loader?limit=100000'
      },
      {
        test: /\.(jpe?g|png|gif|svg)$/i,
        use: [
          'file-loader?limit=100000',
          {
            loader: 'img-loader',
            options: {
              enabled: true,
              optipng: true
            }
          }
        ]
      }
    ]
  },
  plugins: [
    new webpack.DefinePlugin(GLOBALS),
    // create CSS file with all used styles
    new ExtractTextPlugin({
      filename: './css/[name].bundle.css',
      allChunks: true
    }),
    // create popup.html from template and inject styles and script bundles
    new HtmlWebpackPlugin({
      inject: true,
      chunks: ['popup'],
      filename: 'popup.html',
      template: './src/popup.html'
    }),
    // copy extension manifest and icons
    new CopyWebpackPlugin([
      { from: './src/manifest.json' },
      { context: './src/img', from: '*', to: 'img' }
    ])
  ]
}