Webpack and @wordpress/scripts

Initialize package.json

npm init -y

Install wp-cli

npm install wp-cli --save-dev

Install WordPress Scripts for Webpack

npm install @wordpress/scripts --save-dev

Install Sass Loader

npm install sass-loader sass webpack --save-dev

Install MiniCssExtractPlugin

npm install --save-dev mini-css-extract-plugin

webpack.config.js

const path = require('path');
const MiniCssExtractPlugin = require('mini-css-extract-plugin');

module.exports = {
  mode: 'development',
  entry: './assets/src/js/index.js',
  output: {
    filename: 'main.js',
    path: path.resolve(__dirname, 'assets/dist'),
  },
  module: {
    rules: [
      {
        test: /\.scss$/,
        use: [MiniCssExtractPlugin.loader, 'css-loader', 'sass-loader'],
      },
    ],
  },
  plugins: [
    new MiniCssExtractPlugin({
      filename: 'style.css',
    }),
  ],
};

package.json

"scripts": {
    "build": "wp-scripts build",
    "start": "wp-scripts start",
    "dev": "wp-scripts start",
    "devFast": "wp-scripts start",
    "test": "echo \"Error: no test specified\" && exit 1"
  },

Enqueue compiled JavaScript in WordPress

function enqueue_theme_scripts() {
    wp_enqueue_script('main-js', get_template_directory_uri() . '/assets/dist/main.js', array(), '1.0.0', true);
    wp_enqueue_style('style-css', get_template_directory_uri() . '/assets/dist/style.css');
}
add_action('wp_enqueue_scripts', 'enqueue_theme_scripts');