Webpack 4 doc example

webpack.config.js

const path = require('path');

module.exports = {
  mode: "production", // "production" | "development" | "none"
  // Chosen mode tells webpack to use its built-in optimizations accordingly.
  entry: "./app/entry", // string | object | array
  // defaults to ./src
  // Here the application starts executing
  // and webpack starts bundling
  output: {
    // options related to how webpack emits results
    path: path.resolve(__dirname, "dist"), // string
    // the target directory for all output files
    // must be an absolute path (use the Node.js path module)
    filename: "bundle.js", // string
    // the filename template for entry chunks
    publicPath: "/assets/", // string
    // the url to the output directory resolved relative to the HTML page
    library: "MyLibrary", // string,
    // the name of the exported library
    libraryTarget: "umd", // universal module definition
    // the type of the exported library
  },
  module: {
    // configuration regarding modules
    rules: [
      // rules for modules (configure loaders, parser options, etc.)
      {
        test: /\.js$/, // extension regex to match
        exclude: /node_modules/, // exclude certain paths. Can be array.
        include: path.resolve(__dirname, '../../source/'), // Path to include, default all. Can be array.
        use: [ // where the loaders are defined
          'babel-loader', // can be string, if there's only loader
          {
            loader: 'another-loader', // can be object, if there's options.
            options: {}
          }
        ]
    ],
  },
  resolve: {
    // options for resolving module requests
    // (does not apply to resolving to loaders)
    modules: [
      "node_modules",
      path.resolve(__dirname, "app")
    ],
    // directories where to look for modules
    extensions: [".js", ".json", ".jsx", ".css"],
    // extensions that are used
    alias: {
      // a list of module name aliases
      "module": "new-module",
      // alias "module" -> "new-module" and "module/path/file" -> "new-module/path/file"
      "only-module$": "new-module",
      // alias "only-module" -> "new-module", but not "only-module/path/file" -> "new-module/path/file"
      "module": path.resolve(__dirname, "app/third/module.js"),
      // alias "module" -> "./app/third/module.js" and "module/file" results in error
      // modules aliases are imported relative to the current context
    },
  },
  performance: {
    hints: "warning", // enum
    maxAssetSize: 200000, // int (in bytes),
    maxEntrypointSize: 400000, // int (in bytes)
    assetFilter: function(assetFilename) {
      // Function predicate that provides asset filenames
      return assetFilename.endsWith('.css') || assetFilename.endsWith('.js');
    }
  },
  devtool: "source-map", // enum
  // enhance debugging by adding meta info for the browser devtools
  // source-map most detailed at the expense of build speed.
  context: __dirname, // string (absolute path!)
  // the home directory for webpack
  // the entry and module.rules.loader option
  //   is resolved relative to this directory
  target: "web", // enum
  // the environment in which the bundle should run
  // changes chunk loading behavior and available modules
  externals: ["react", /^@angular/],
  // Don't follow/bundle these modules, but request them at runtime from the environment
  serve: { //object
    port: 1337,
    content: './dist',
  },
  // lets you provide options for webpack-serve
  stats: "errors-only",
  // lets you precisely control what bundle information gets displayed
  devServer: {
    proxy: { // proxy URLs to backend development server
      '/api': 'http://localhost:3000'
    },
    contentBase: path.join(__dirname, 'public'), // boolean | string | array, static file location
    compress: true, // enable gzip compression
    historyApiFallback: true, // true for index.html upon 404, object for multiple paths
    hot: true, // hot module replacement. Depends on HotModuleReplacementPlugin
    https: false, // true for self-signed, object for cert authority
    noInfo: true, // only errors & warns on hot reload
    // ...
  },
  plugins: [],
}

// docs: https://webpack.js.org/configuration/#use-different-config-file