webpack.dev.js

const path = require('path');
const MiniCssExtractPlugin = require('mini-css-extract-plugin');
const HtmlWebpackPlugin = require('html-webpack-plugin');
const CopyPlugin = require("copy-webpack-plugin");

module.exports = {
  entry: {
    popup: path.resolve('./src/index.js'),
    background: path.resolve('./src/background.js')
  },
  output: {
    path: path.resolve(__dirname, 'dist'),
    filename: '[name].js',
  },
  mode: 'development',
  devtool: 'inline-source-map',
  module: {
    rules: [
      {
        test: /\.js|jsx%/,
        exclude: /node_modules/,
        use: {
          loader: 'babel-loader',
          options: {
            presets: [
              '@babel/preset-env',
              ['@babel/preset-react', {"runtime": "automatic"}]
            ],
          }
        }
      },
      {
        test: /\.css$/i,
        use: [MiniCssExtractPlugin.loader, "css-loader"]
      },
      {
        test: /\.svg$/i,
        use: [
          {
            loader: 'svg-url-loader',
            options: {
              limit: 10000,
            },
          },
        ]
      }
    ]
  },
  plugins: [
    new HtmlWebpackPlugin({
      template: './public/index.html',
      filename: 'popup.html'
    }),
    new MiniCssExtractPlugin(),
    new CopyPlugin({
      patterns: [
        {
          from: "public",
        },
      ],
    }),
  ],
};