webpack.config.js

const path = require('path');
const fs = require('fs');
const {CleanWebpackPlugin} = require('clean-webpack-plugin');
const CopyWebpackPlugin = require('copy-webpack-plugin');
const MiniCssExtractPlugin = require('mini-css-extract-plugin');
const OptimizeCssAssetWebpackPlugin = require('optimize-css-assets-webpack-plugin');
const TerserWebpackPlugin = require('terser-webpack-plugin');
const HtmlWebpackPlugin = require('html-webpack-plugin');
const chokidar = require('chokidar');


const PATHS = {
  src: path.join(__dirname, './src'),
  dist: path.join(__dirname, './dist'),
  assets: 'assets/',
  pages: function () { return `${this.src}/pug/` }
}

const PAGES = fs.readdirSync(PATHS.pages()).filter(fileName => fileName.endsWith('.pug'));

const isDev = process.env.NODE_ENV === 'development'
const isProd = !isDev

const optimization = () => {
  const config = {};

  if (isProd) {
    config.minimizer = [
      new OptimizeCssAssetWebpackPlugin(),
      new TerserWebpackPlugin()
    ]
  }

  return config
}

const filename = ext => isDev ? `[name].${ext}` : `[name].[contenthash].${ext}`


const jsLoaders = () => {
  const loaders = [{
    loader: 'babel-loader',
    options: {
      presets: [
        '@babel/preset-env'
      ],
      plugins: [
        '@babel/plugin-proposal-class-properties'
      ]
    }
  }]

  if (isDev) {
    loaders.push('eslint-loader')
  }

  return loaders
}

const plugins = () => {
  const base = [
    new CleanWebpackPlugin(),
    new CopyWebpackPlugin([
      { from: `${PATHS.src}/${PATHS.assets}img`, to: `${PATHS.assets}img` },
      { from: `${PATHS.src}/${PATHS.assets}fonts`, to: `${PATHS.assets}fonts` },
      { from: `${PATHS.src}/static`, to: '' },
    ]),
    new MiniCssExtractPlugin({
      filename: filename('css')
    }),
    ...PAGES.map(page => new HtmlWebpackPlugin({
      template: `${PATHS.pages()}/${page}`,
      filename: `./${page.replace(/\.pug/,'.html')}`,
      inject: 'body'
    }))
  ]


  return base
}

module.exports = {
  mode: process.env.NODE_ENV,
  entry: {
    app: PATHS.src,
  },
  output: {
    filename: 'ramabot.js',
    path: PATHS.dist
  },
  optimization: optimization(),
  devServer: {
    hot: true,
    overlay: {
      warnings: false,
      errors: true
    },
    before(app, server) {
      chokidar.watch([
        `${PATHS.src}/**/*.pug`
      ]).on('all', function() {
        server.sockWrite(server.sockets, 'content-changed');
      })
    }
  },
  devtool: isDev ? 'source-map' : '',
  plugins: plugins(),
  module: {
    rules: [
      {
        test: /\.pug$/,
        loader: 'pug-loader',
        options: {
          pretty: true
        }
      },
      {
        test: /\.css$/,
        use: [
          'css-loader',
          {
            loader: MiniCssExtractPlugin.loader,
            options: {
              hmr: isDev,
              reloadAll: true
            },
          },
        ]
      },
      {
        test: /\.s[ac]ss$/,
        use: [
          'style-loader',
          {
            loader: 'css-loader',
            options: {
              sourceMap: true,
            },
          },
          {
            loader: 'sass-loader',
            options: {
              sourceMap: true,
            },
          },
        ],
      },
      {
        test: /\.(png|jpg|svg|gif)$/,
        use: ['file-loader']
      },
      {
        test: /\.(ttf|woff|woff2|eot)$/,
        use: ['file-loader']
      },
      {
        test: /\.xml$/,
        use: ['xml-loader']
      },
      {
        test: /\.csv$/,
        use: ['csv-loader']
      },
      {
        test: /\.js$/,
        exclude: /node_modules/,
        use: jsLoaders()
      }
    ]
  }
}