old_contents: const path = require('path');
  const webpack = require('webpack');
  
  const base = require('./webpack.config.base');
  
  const config = base('production');
  
  module.exports = Object.assign({}, config, {
      output: Object.assign({}, config.output, {
          path: path.join(__dirname, '..', 'examples', 'assets'),
      }),
  
      plugins: config.plugins.concat([
          new webpack.optimize.UglifyJsPlugin({
              compress: {
                  warnings: false,
                  // Disabled because of an issue with Uglify breaking seemingly valid code:
                  // https://github.com/facebookincubator/create-react-app/issues/2376
                  // Pending further investigation:
                  // https://github.com/mishoo/UglifyJS2/issues/2011
                  comparisons: false,
              },
              mangle: {
                  safari10: true,
              },
              output: {
                  comments: false,
                  // Turned on because emoji and regex is not minified properly using default
                  // https://github.com/facebookincubator/create-react-app/issues/2488
                  ascii_only: true,
              },
          }),
      ]),
  });
  
new_contents: const path = require('path');
  const webpack = require('webpack');
  
  const base = require('./webpack.config.base');
  
  const config = base('production');
  
  module.exports = Object.assign({}, config, {
      // See http://webpack.github.io/docs/configuration.html#devtool
      devtool: 'source-map',
  
      output: Object.assign({}, config.output, {
          path: path.join(__dirname, '..', 'examples', 'assets'),
      }),
  
      plugins: config.plugins.concat([
          new webpack.optimize.UglifyJsPlugin({
              compress: {
                  warnings: false,
                  // Disabled because of an issue with Uglify breaking seemingly valid code:
                  // https://github.com/facebookincubator/create-react-app/issues/2376
                  // Pending further investigation:
                  // https://github.com/mishoo/UglifyJS2/issues/2011
                  comparisons: false,
              },
              mangle: {
                  safari10: true,
              },
              output: {
                  comments: false,
                  // Turned on because emoji and regex is not minified properly using default
                  // https://github.com/facebookincubator/create-react-app/issues/2488
                  ascii_only: true,
              },
          }),
      ]),
  });
  
subject: Use source maps in production build