text: const webpack = require('webpack');
  const webpackMerge = require('webpack-merge');
  const CleanWebpackPlugin = require('clean-webpack-plugin');
  const HtmlWebpackPlugin = require('html-webpack-plugin');
  const commonConfig = require('./webpack.common');
  const { ENV, dir } = require('./helpers');
  const { CheckerPlugin } = require('awesome-typescript-loader');
  
  module.exports = function(env) {
    return webpackMerge(commonConfig({ env: ENV }), {
      devtool: 'source-map',
      entry: {
        'app': './demo/bootstrap.ts',
        'libs': './demo/libs.ts'
      },
      module: {
        exprContextCritical: false,
        rules: [
          {
            enforce: 'pre',
            test: /\.js$/,
            loader: 'source-map-loader',
            exclude: /(node_modules)/
          },
          {
            test: /\.ts$/,
            loaders: [
              'awesome-typescript-loader',
              'angular2-template-loader'
            ],
            exclude: [/\.(spec|e2e|d)\.ts$/]
          }
        ]
      },
      plugins: [
        new CheckerPlugin(),
        new webpack.optimize.CommonsChunkPlugin({
          name: ['libs'],
          minChunks: Infinity
        }),
        new HtmlWebpackPlugin({
          template: 'demo/index.ejs',
          chunksSortMode: 'dependency',
          title: 'ngx-charts',
          googleAnalytics: {
            trackingId: 'UA-57474611-3',
            pageViewOnLoad: true
          }
        }),
        new CleanWebpackPlugin(['dist'], {
          root: dir(),
          verbose: false,
          dry: false
        }),
        new webpack.optimize.UglifyJsPlugin()
      ]
    });
  
  };
  