Webpack and .NET Core

Question

I have created a .NET Core Angular 5 SPA in Visual Studio 2017. I am very confused about the way Webpack works in the above. For example, there are no scripts for Webpack inside package.json:

{
  "private": true,
  "version": "0.0.0",
  "scripts": {
    "test": "karma start ClientApp/test/karma.conf.js"
  },
  "dependencies": {
    "@angular/animations": "^5.0.2",
    "@angular/cdk": "^5.0.0-rc.1",
    "@angular/common": "^5.0.2",
    "@angular/compiler": "^5.0.2",
    "@angular/compiler-cli": "^5.0.2",
    "@angular/core": "^5.0.2",
    "@angular/forms": "^5.0.2",
    "@angular/http": "^5.0.2",
    "@angular/material": "^5.0.0-rc.1",
    "@angular/platform-browser": "^5.0.2",
    "@angular/platform-browser-dynamic": "^5.0.2",
    "@angular/platform-server": "^5.0.2",
    "@angular/router": "^5.0.2",
    "@ngtools/webpack": "1.8.3",
    "@types/webpack-env": "1.13.2",
    "angular2-template-loader": "0.6.2",
    "aspnet-prerendering": "^3.0.1",
    "aspnet-webpack": "^2.0.1",
    "awesome-typescript-loader": "3.4.0",
    "bootstrap": "3.3.7",
    "css": "2.2.1",
    "css-loader": "0.28.7",
    "es6-shim": "0.35.3",
    "event-source-polyfill": "0.0.12",
    "expose-loader": "0.7.4",
    "extract-text-webpack-plugin": "3.0.2",
    "file-loader": "1.1.5",
    "html-loader": "0.5.1",
    "isomorphic-fetch": "2.2.1",
    "jquery": "3.2.1",
    "json-loader": "0.5.7",
    "preboot": "5.1.7",
    "raw-loader": "0.5.1",
    "reflect-metadata": "0.1.10",
    "rxjs": "^5.5.2",
    "style-loader": "0.19.0",
    "to-string-loader": "1.1.5",
    "typescript": "2.6.1",
    "url-loader": "0.6.2",
    "webpack": "3.8.1",
    "webpack-hot-middleware": "2.20.0",
    "webpack-merge": "4.1.1",
    "zone.js": "0.8.18"
  },
  "devDependencies": {
    "@types/chai": "4.0.5",
    "@types/jasmine": "2.8.2",
    "chai": "4.1.2",
    "jasmine-core": "2.8.0",
    "karma": "1.7.1",
    "karma-chai": "0.1.0",
    "karma-chrome-launcher": "2.2.0",
    "karma-cli": "1.0.1",
    "karma-jasmine": "1.1.0",
    "karma-webpack": "2.0.6"
  }
}

Could you please explain to me how Webpack comes into play? Here is the webpack.config.js file:

const path = require('path');
const webpack = require('webpack');
const merge = require('webpack-merge');
const AotPlugin = require('@ngtools/webpack').AotPlugin;
const CheckerPlugin = require('awesome-typescript-loader').CheckerPlugin;

module.exports = (env) => {
    // Configuration in common to both client-side and server-side bundles
    const isDevBuild = !(env && env.prod);
    const sharedConfig = {
        stats: { modules: false },
        context: __dirname,
        resolve: { extensions: [ '.js', '.ts' ] },
        output: {
            filename: '[name].js',
            publicPath: 'dist/' // Webpack dev middleware, if enabled, handles requests for this URL prefix
        },
        module: {
            rules: [
                { test: /\.ts$/, include: /ClientApp/, use: isDevBuild ? ['awesome-typescript-loader?silent=true', 'angular2-template-loader'] : '@ngtools/webpack' },
                { test: /\.html$/, use: 'html-loader?minimize=false' },
                { test: /\.css$/, use: [ 'to-string-loader', isDevBuild ? 'css-loader' : 'css-loader?minimize' ] },
                { test: /\.(png|jpg|jpeg|gif|svg)$/, use: 'url-loader?limit=25000' }
            ]
        },
        plugins: [new CheckerPlugin()]
    };

    // Configuration for client-side bundle suitable for running in browsers
    const clientBundleOutputDir = './wwwroot/dist';
    const clientBundleConfig = merge(sharedConfig, {
        entry: { 'main-client': './ClientApp/boot.browser.ts' },
        output: { path: path.join(__dirname, clientBundleOutputDir) },
        plugins: [
            new webpack.DllReferencePlugin({
                context: __dirname,
                manifest: require('./wwwroot/dist/vendor-manifest.json')
            })
        ].concat(isDevBuild ? [
            // Plugins that apply in development builds only
            new webpack.SourceMapDevToolPlugin({
                filename: '[file].map', // Remove this line if you prefer inline source maps
                moduleFilenameTemplate: path.relative(clientBundleOutputDir, '[resourcePath]') // Point sourcemap entries to the original file locations on disk
            })
        ] : [
            // Plugins that apply in production builds only
            new webpack.optimize.UglifyJsPlugin(),
            new AotPlugin({
                tsConfigPath: './tsconfig.json',
                entryModule: path.join(__dirname, 'ClientApp/app/app.module.browser#AppModule'),
                exclude: ['./**/*.server.ts']
            })
        ])
    });

    // Configuration for server-side (prerendering) bundle suitable for running in Node
    const serverBundleConfig = merge(sharedConfig, {
        resolve: { mainFields: ['main'] },
        entry: { 'main-server': './ClientApp/boot.server.ts' },
        plugins: [
            new webpack.DllReferencePlugin({
                context: __dirname,
                manifest: require('./ClientApp/dist/vendor-manifest.json'),
                sourceType: 'commonjs2',
                name: './vendor'
            })
        ].concat(isDevBuild ? [] : [
            // Plugins that apply in production builds only
            new AotPlugin({
                tsConfigPath: './tsconfig.json',
                entryModule: path.join(__dirname, 'ClientApp/app/app.module.server#AppModule'),
                exclude: ['./**/*.browser.ts']
            })
        ]),
        output: {
            libraryTarget: 'commonjs',
            path: path.join(__dirname, './ClientApp/dist')
        },
        target: 'node',
        devtool: 'inline-source-map'
    });

    return [clientBundleConfig, serverBundleConfig];
};

Moreover, there is another file named webpack.config.vendor.js. What exactly is that?

Answer 1

All of the webpack stuff is taken care of by the MSBuild process (and corresponding middleware). In order to find the references you are looking for, take a look at the .csproj file for your project. Here's an example taken from one I have generated:

<Target Name="DebugRunWebpack" BeforeTargets="Build" ... ">
    ...

    <Message Importance="high" Text="Performing first-run Webpack build..." />
    <Exec Command="node node_modules/webpack/bin/webpack.js --config webpack.config.vendor.js" />
    <Exec Command="node node_modules/webpack/bin/webpack.js" />
</Target>

The reason for the two config files is simple: one is for your code, assets, etc and the other is for vendor code, assets, etc, including angular, bootstrap and jQuery.