webpack-plugin.ts

/**
 * @license
 * Copyright Google Inc. All Rights Reserved.
 *
 * Use of this source code is governed by an MIT-style license that can be
 * found in the LICENSE file at https://angular.io/license
 */
import { Compiler, WebpackFourCompiler } from 'webpack';

interface ModuleData {
  resourceResolveData: { descriptionFileData?: { typings?: string } };
}

export class BuildOptimizerWebpackPlugin {
  apply(compiler: Compiler | WebpackFourCompiler) {
    (compiler as Compiler).hooks.normalModuleFactory.tap('BuildOptimizerWebpackPlugin', nmf => {
      // tslint:disable-next-line: no-any
      nmf.hooks.module.tap('BuildOptimizerWebpackPlugin', (module, data) => {
        const { descriptionFileData } = (data as ModuleData).resourceResolveData;
        if (descriptionFileData) {
          // Only TS packages should use Build Optimizer.
          // Notes:
          // - a TS package might not have defined typings but still use .d.ts files next to their
          // .js files. We don't cover that case because the Angular Package Format (APF) calls for
          // using the Typings field and Build Optimizer is geared towards APF. Maybe we could
          // provide configuration options to the plugin to cover that case if there's demand.
          // - a JS-only package that also happens to provides typings will also be flagged by this
          // check. Not sure there's a good way to skip those.
          const skipBuildOptimizer = !descriptionFileData.typings;
          module.factoryMeta = { ...module.factoryMeta, skipBuildOptimizer };
        }

        return module;
      });
    });
  }
}