title: Unicode characters not showed when bundling and deploying React app with webpack and babel
body: <p>On my local environment, unicode characters work fine but when I run webpack to bundle and deploy, string which is like "\uf00c" becomes "" in index_bundle.js</p>
  
  <p>I think there's a problem in babel config or webpack config but I can't resolve it as I'm new to the whole stack.</p>
  
  <p>Here is the codes:</p>
  
  <pre><code>&lt;Label className="switch switch-icon switch-pill switch-success"&gt;
     &lt;Input type="checkbox" className="switch-input" defaultChecked onChange={this.handleActivateUser.bind(this, user.id)}/&gt;
        &lt;span className="switch-label" data-on={'\uf00c'} data-off={'\uf00d'}&gt;&lt;/span&gt;
        &lt;span className="switch-handle"&gt;&lt;/span&gt;
  &lt;/Label&gt;
  </code></pre>
  
  <p>My .babelrc:</p>
  
  <pre><code>{
     "presets": [
       ["env"], ["react"]
     ],
     "plugins": ["transform-class-properties", "transform-object-rest-spread"]
  }
  </code></pre>
  
  <p>And my webpack.config.js:</p>
  
  <pre><code>var path = require('path');
  var HtmlWebpackPlugin = require('html-webpack-plugin');
  const ExtractTextPlugin = require('extract-text-webpack-plugin');
  const CopyWebpackPlugin = require('copy-webpack-plugin');
  const extractCSS = new ExtractTextPlugin('[name].fonts.css');
  const extractSCSS = new ExtractTextPlugin('[name].styles.css');
  const webpackUglifyJsPlugin = require('webpack-uglify-js-plugin');
  var webpack = require('webpack');
  config = {
    entry: ['babel-polyfill', 'whatwg-fetch', './app/index.js'],
    output: {
      path: path.resolve(__dirname, 'dist'),
      filename: 'index_bundle.js',
      publicPath: '/'
    },
    module: {
      rules: [
        {
          test: /\.(js|jsx)$/,
          exclude: /node_modules/,
          use: 'babel-loader'
        },
        {
            test: /\.(scss)$/,
            use: ['css-hot-loader'].concat(extractSCSS.extract({
              fallback: 'style-loader',
              use: [
                {
                  loader: 'css-loader',
                  options: {alias: {'../img': '../public/img'}}
                },
                {
                  loader: 'sass-loader'
                }
              ]
            }))
          },
          {
            test: /\.css$/,
            use: extractCSS.extract({
              fallback: 'style-loader',
              use: 'css-loader'
            })
          },
          {
            test: /\.(png|jpg|jpeg|gif|ico)$/,
            use: [
              {
                // loader: 'url-loader'
                loader: 'file-loader',
                options: {
                  name: './img/[name].[hash].[ext]'
                }
              }
            ]
          },
          {
            test: /\.(woff(2)?|ttf|eot|svg)(\?v=\d+\.\d+\.\d+)?$/,
            use: [
              {
                // loader: 'url-loader'
                loader: 'file-loader',
                options: {
                  name: './fonts/[name].[hash].[ext]'
                }
              }
            ]
          }
      ]
    },
    devServer: {
      historyApiFallback: true
    },
    plugins: [
      new HtmlWebpackPlugin({
        template: 'app/index.html'
      }),
      extractCSS,
      extractSCSS,
      new CopyWebpackPlugin([
          {from: './public/img', to: 'img'}
        ],
        {copyUnmodified: false}
      )
    ]
  }
  module.exports = config;
  </code></pre>