Unable to achieve the same level of bundle optimization with webpack + angular as compared to angular-cli

Question

I have two identical Angular projects, one an angular-cli and another a Webpack version using @ngtools/webpack. Both projects are running Angular 7.1.4 and @angular-devkit 0.13.5. The Angular code is the initial app module/component that is generated with the angular-cli.

The issue I am having is that the Webpack version is generating a compressed app bundle of 450 KB but the angular-cli's bundle is 238 KB. Without the TerserPlugin, the angular-cli's app bundle is 1.51 MB and Webpack's output is 1.62 MB.

For angular-cli, I am running "ng build --prod=true" with this config:

"production": {
  "fileReplacements": [
    {
      "replace": "src/environments/environment.ts",
      "with": "src/environments/environment.prod.ts"
    }
  ],
  "optimization": true,
  "outputHashing": "all",
  "sourceMap": false,
  "extractCss": true,
  "namedChunks": false,
  "aot": true,
  "extractLicenses": true,
  "vendorChunk": false,
  "buildOptimizer": true,
  "budgets": [
    {
      "type": "initial",
      "maximumWarning": "2mb",
      "maximumError": "5mb"
    }
  ]
}

And here is my Webpack config:

{
    mode: 'production',
    entry: {
        app: './src/main',
    },
    output: {
        path: path.resolve(__dirname, 'public'),
        filename: "[id].[chunkhash].js",
        chunkFilename: "[id].[chunkhash].js",
    },
    resolve: {
        extensions: ['.ts', '.tsx', '.mjs', '.js'],
    },
    module: {
        rules: [
            {
                test: /\.html$/,
                loader: 'raw-loader',
            },
            {
                test: /\.scss$/,
                use: [
                    'to-string-loader',
                    {
                        loader: 'css-loader',
                        options: {
                            sourceMap: false
                        }
                    },
                    {
                        loader: 'sass-loader',
                        options: {
                            sourceMap: false
                        }
                    },
                ]
            },
            {
                test: /\.(eot|svg|cur|jpg|png|webp|gif|otf|ttf|woff|woff2|ani)$/,
                loader: 'file-loader',
            },
            {
                test: /(?:\.ngfactory\.js|\.ngstyle\.js|\.ts)$/,
                loader: '@ngtools/webpack'
            },
            {
                test: /[\/\\]@angular[\/\\]core[\/\\].+\.js$/,
                parser: { system: true },
            },
            {
                test: /\.js$/,
                use: [
                    {
                        loader: '@angular-devkit/build-optimizer/webpack-loader',
                        options: { sourceMap: false },
                    },
                ],
            },
        ]
    },
    optimization: {
        minimizer: [
            new TerserPlugin({
                cache: true,
                terserOptions: {
                    compress: {
                        pure_getters: true,
                        passes: 3,
                        global_defs: {
                            ngDevMode: false,
                        },
                    },
                    output: {
                        ascii_only: true,
                        comments: false,
                        safari10: true,
                        webkit: true,
                    },
                },
            })
        ],
        providedExports: true,
        usedExports: true,
        concatenateModules: true,
        runtimeChunk: true,
    },
    plugins: [
        new AngularCompilerPlugin({
            tsConfigPath: path.resolve(__dirname, './tsconfig.json'),
            entryModule: path.resolve(__dirname, './src/app/app.module#AppModule'),
            mainPath: path.resolve(__dirname, './src/main.ts'),
        })
    ]
};

Looking at the bundles with BundleAnalyzerPlugin, the stat size of node_modules is 1.52 MB for both projects, but the angular-cli's parsed size is 238 KB vs 441 KB for Webpack's. From what I can tell, there is about 100 KB of difference in the node_modules, even though the packages, such as rxjs, are the same version.

angular-cli:

Webpack:

What is going on, and how can I achieve the same level of optimization for both projects?

Answer 1

It looks like the issue in the Webpack project was that the tsconfig "module" setting was "commonjs". Changing it to "es2015", like defaulted in an angular-cli app, now compiles the app down to 248 KB.