angular-cli/addon/ng2/tasks/build-webpack.ts

import * as rimraf from 'rimraf';
import * as path from 'path';
import * as Task from 'ember-cli/lib/models/task';
import * as webpack from 'webpack';
import { ServeTaskOptions } from '../commands/serve';
import { NgCliWebpackConfig } from '../models/webpack-config';
import { webpackOutputOptions } from '../models/';

// Configure build and output;
let lastHash: any = null;

module.exports = Task.extend({
  // Options: String outputPath
  run: function(runTaskOptions: ServeTaskOptions) {

    var project = this.cliProject;

    rimraf.sync(path.resolve(project.root, runTaskOptions.outputPath));
    var config = new NgCliWebpackConfig(project, runTaskOptions.target, runTaskOptions.environment, runTaskOptions.outputPath).config;
    
    const webpackCompiler = webpack(config);

    const ProgressPlugin  = require('webpack/lib/ProgressPlugin');

    webpackCompiler.apply(new ProgressPlugin({
      profile: true
    }));

    return new Promise((resolve, reject) => {
      webpackCompiler.run((err, stats) => {
        // Don't keep cache
        // TODO: Make conditional if using --watch
        webpackCompiler.purgeInputFileSystem();

        if(err) {
          lastHash = null;
          console.error(err.stack || err);
          if(err.details) console.error(err.details);
            reject(err.details);
        }

        if(stats.hash !== lastHash) {
          lastHash = stats.hash;
          process.stdout.write(stats.toString(webpackOutputOptions) + "\n");
        }
        resolve();
      });
    });
  }
});