webpack.config.js

const path = require('path');
const CopyPlugin = require('copy-webpack-plugin');

module.exports = {
  mode: 'development',
  entry: {
    background: './src/background/index.js',
    content: './src/content/index.js',
    popup: './src/popup/index.js'
  },
  output: {
    filename: '[name].js',
    path: path.resolve(__dirname, 'dist'),
    clean: true
  },
  module: {
    rules: [
      {
        test: /\.js$/,
        exclude: /node_modules/,
        use: {
          loader: 'babel-loader',
          options: {
            presets: ['@babel/preset-env']
          }
        }
      },
      {
        test: /\.css$/,
        use: ['style-loader', 'css-loader']
      },
      {
        test: /\.(png|jpg|jpeg|gif|svg)$/,
        type: 'asset/resource',
        generator: {
          filename: 'assets/[name][ext]'
        }
      }
    ]
  },
  plugins: [
    new CopyPlugin({
      patterns: [
        {
          from: 'src/manifest.json',
          to: 'manifest.json',
          transform(content) {
            return Buffer.from(
              JSON.stringify({
                ...JSON.parse(content.toString()),
                version: process.env.npm_package_version
              })
            );
          }
        },
        { from: 'assets', to: 'assets' }
      ]
    })
  ],
  devtool: 'source-map',
  optimization: {
    splitChunks: {
      chunks: 'all'
    }
  }
};