webpack.config.js

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

module.exports = {
  entry: {
    index: './src/index.js',
    background: './src/background/background.js',
    contentScript: './src/contentScript/contentScript.js',
  },
  mode: 'production',
  module: {
    rules: [
      {
        test: /\.js$/,
        exclude: /node_modules/,
        use: {
          loader: 'babel-loader',
          options: {
            presets: ['@babel/preset-env', '@babel/preset-react'],
          },
        },
      },
      {
        test: /\.css$/i,
        exclude: /node_modules/,
        use: ['style-loader', 'css-loader'],
      },
    ],
  },
  plugins: [
    new CopyPlugin({
      patterns: [
        { from: 'manifest.json', to: 'manifest.json' },
      ],
    }),
    new HTMLPlugin({
      template: './public/index.html',
      filename: 'index.html',
      chunks: ['index'],
    }),
  ],
  resolve: {
    extensions: ['.js', '.jsx'],
  },
  output: {
    path: path.resolve(__dirname, 'dist'),
    filename: 'js/[name].js',
  },
};