classic themeing: webpack sample gist

app.js

import './scss/style.scss';

// Example jQuery usage:
$(document).ready(() => {
  $('h1').css('color', 'red');
});

package.json

{
  "name": "fictional-university-theme",
  "version": "1.0.0",
  "description": "A fictional university WordPress theme.",
  "main": "index.js",
  "scripts": {
    "dev": "webpack serve --config webpack.config.js --env.mode=development",
    "build": "webpack --config webpack.config.js --env.mode=production"
  },
  "author": "",
  "license": "ISC",
  "dependencies": {
    "@babel/core": "^7.15.8",
    "@babel/preset-env": "^7.15.8",
    "@babel/preset-react": "^7.14.5",
    "autoprefixer": "^10.4.2",
    "babel-loader": "^8.2.3",
    "clean-webpack-plugin": "^4.0.0",
    "css-loader": "^6.5.1",
    "css-minimizer-webpack-plugin": "^7.0.0",
    "fse": "^3.0.1",
    "mini-css-extract-plugin": "^2.5.2",
    "postcss-color-function": "^5.0.0",
    "postcss-hexrgba": "^4.0.0",
    "postcss-import": "^14.0.2",
    "postcss-mixins": "^7.0.0",
    "postcss-nested": "^5.0.5",
    "postcss-simple-vars": "^6.0.3",
    "postcss-loader": "^6.2.1",
    "terser-webpack-plugin": "^6.0.0",
    "webpack": "^5.64.4",
    "webpack-cli": "^4.9.1",
    "webpack-dev-server": "^4.6.0",
    "webpack-manifest-plugin": "^5.3.2"
  }
}

webpack.config.js

	const path = require('path');
const settings = require('./settings');
const webpack = require('webpack');
const MiniCssExtractPlugin = require('mini-css-extract-plugin');
const OptimizeCSSAssetsPlugin = require('optimize-css-assets-webpack-plugin');
const TerserJSPlugin = require('terser-webpack-plugin');
const HtmlWebpackPlugin = require('html-webpack-plugin');
const { CleanWebpackPlugin } = require('clean-webpack-plugin');

module.exports = (env, options) => {
  const isDevelopment = options.mode === 'development';

  return {
    entry: './src/index.js',
    output: {
      path: path.resolve(__dirname, 'dist'),
     filename: 'bundle.js',
    },
   devServer: {
    contentBase: './dist',
    watchContentBase: true,
    watchOptions: {
      poll: !!parseInt(settings.devServerConfig.poll()),
      ignored: /node_modules/,
    },
    optimization: {
      minimizer: [
        new TerserJSPlugin({}),
        new OptimizeCSSAssetsPlugin({})
      ],
      splitChunks: {
        chunks: 'all'
      }
    },
    module: {
      rules: [
        {
          test: /\.js$/,
          exclude: /node_modules/,
          use: {
            loader: 'babel-loader',
            options: {
              presets: ['@babel/preset-env']
            }
          }
        },
        {
          test: /\.(sa|sc|c)ss$/,
          use: [
            isDevelopment ? 'style-loader' : MiniCssExtractPlugin.loader,
            'css-loader',
            'postcss-loader',
            'sass-loader'
          ]
        },
        {
          test: /\.(png|svg|jpg|gif)$/,
          use: [
            'file-loader'
          ]
        },
        {
          test: /\.css$/i,
          use: [
            isDevelopment ? 'style-loader' : MiniCssExtractPlugin.loader,
            'css-loader',
            'postcss-loader'
          ]
        }
      ]
    },
    plugins: [
      new webpack.ProvidePlugin({
        $: 'jquery',
        jQuery: 'jquery'
      }),
      new MiniCssExtractPlugin({
        filename: isDevelopment ? '[name].css' : '[name].[contenthash].css',
        chunkFilename: isDevelopment ? '[id].css' : '[id].[contenthash].css'
      }),
      new HtmlWebpackPlugin({
        template: 'src/index.html',
        filename: 'index.php',
        minify: {
          collapseWhitespace: true,
          removeComments: true,
          removeRedundantAttributes: true,
          removeScriptTypeAttributes: true,
          removeStyleLinkTypeAttributes: true,
          useShortDoctype: true
        }
      }),
      new webpack.HotModuleReplacementPlugin(),
      new webpack.DefinePlugin({
        'process.env.NODE_ENV': JSON.stringify(process.env.NODE_ENV || 'development')
      }),
      new CleanWebpackPlugin()
    ],
    devtool: 'eval-cheap-module-source-map',
    performance: {
      maxAssetSize: 500000,
      maxEntrypointSize: 500000
    }
  };
};