webpack boiler

const CleanWebpackPlugin = require('clean-webpack-plugin');
const HtmlWebpackPlugin = require('html-webpack-plugin');
const MiniCssExtractPlugin = require("mini-css-extract-plugin");
const OptimizeCSSAssetsPlugin = require("optimize-css-assets-webpack-plugin");
const MinifyPlugin = require("babel-minify-webpack-plugin");
const path = require('path');

module.exports = function (env, argv) {
  return {
    mode: 'production',
    entry: [
      './src/app.js'
    ],
    optimization: {
      minimizer: [
        new OptimizeCSSAssetsPlugin()
      ]
    }
    ,
    plugins: [
      new CleanWebpackPlugin(['dist']),
      new HtmlWebpackPlugin({
        title: 'Webpack starter project',
        template: path.resolve('./src/index.html')
      }),
      new MiniCssExtractPlugin({
        filename: "[name].css",
        chunkFilename: "[id].css"
      }),
      new MinifyPlugin()
    ],
    module: {
      rules: [
        {
          test: /\.scss$/,
          use: [
            MiniCssExtractPlugin.loader,
            "css-loader",
            "sass-loader"
          ]
        },
        {
          test: /\.m?js$/,
          exclude: /(node_modules|bower_components)/,
          use: {
            loader: 'babel-loader',
            options: {
              presets: ['@babel/preset-env']
            }
          }
        },
        {
          test: /\.(pdf|doc|docx|xls|xlsx|txt|csv|tsv)$/,
          use: [
            {
              loader: "file-loader",
              options: {
                outputPath: './files',
                name: "[name].[ext]",
              },
            }
          ]
        },
        {
          test: /\.(jpg|jpeg|gif|png|svg|webp)$/,
          use: [
            {
              loader: "file-loader",
              options: {
                outputPath: './images',
                name: "[name].[ext]",
              },
            },
            {
              loader: 'image-webpack-loader',
              options: {
                mozjpeg: {
                  progressive: false,
                  quality: 45
                },
                // optipng.enabled: false will disable optipng
                optipng: {
                  enabled: true,
                },
                pngquant: {
                  quality: '65-90',
                  speed: 4
                },
                gifsicle: {
                  interlaced: true,
                  optimizationLevel: 3
                },
                // the webp option will enable WEBP
                webp: {
                  quality: 20
                }
              }
            },
          ],
        },
        {
          test: /\.(woff(2)?|ttf|otf|eot|svg)(\?v=\d+\.\d+\.\d+)?$/,
          use: [
            {
              loader: 'file-loader',
              options: {
                name: '[name].[ext]',
                outputPath: 'fonts/'
              }
            }
          ]
        },
        {
          test: /\.html$/,
          use: {
            loader: 'html-loader',
            options: {
              attrs: [':src', ':href']
            }
          }
        },
      ]
    }
  };
}

webpack.config.js

const HtmlWebpackPlugin = require('html-webpack-plugin');
const webpack = require('webpack');
const path = require('path');

module.exports = function(){
  return {
    mode: 'development',
    entry: [
      './src/app.js'
    ],
    watch: true,
    watchOptions: {
      aggregateTimeout: 300, // Process all changes which happened in this time into one rebuild
      poll: 1000, // Check for changes every second,
      ignored: /node_modules/,
      // ignored: [
      //   '**/*.scss', '/node_modules/'
      // ]
    },
    devtool: 'source-maps',
    devServer: {
      contentBase: path.join(__dirname, 'src'),
      watchContentBase: true,
      hot: true,
      open: true,
      inline: true
    },
    plugins: [
      new HtmlWebpackPlugin({
        title: 'Webpack starter project',
        template: path.resolve('./src/index.html')
      }),
      new webpack.HotModuleReplacementPlugin()
    ],
    module: {
      rules: [
        {
          test: /\.scss$/,
          use: [
            'style-loader',
            "css-loader",
            "sass-loader"
          ]
        },
        {
          test: /\.m?js$/,
          exclude: /(node_modules|bower_components)/,
          use: {
            loader: 'babel-loader',
            options: {
              presets: ['@babel/preset-env']
            }
          }
        },
        {
          test: /\.(pdf|doc|docx|xls|xlsx|txt|csv|tsv)$/,
          use: [
            {
              loader: "file-loader",
              options: {
                outputPath: './files',
                name: "[name].[ext]",
              },
            }
          ]
        },
        {
          test: /\.(jpg|jpeg|gif|png|svg|webp)$/,
          use: [
            {
              loader: "file-loader",
              options: {
                outputPath: './images',
                name: "[name].[ext]",
              },
            },
          ]
        },
        {
          test: /\.(woff(2)?|ttf|otf|eot|svg)(\?v=\d+\.\d+\.\d+)?$/,
          use: [
            {
              loader: 'file-loader',
              options: {
                name: '[name].[ext]',
                outputPath: 'fonts/'
              }
            }
          ]
        },
        {
          test: /\.html$/,
          use: {
            loader: 'html-loader',
            options: {
              attrs: [':src', ':href']
            }
          }
        },
      ]
    }
  };
}