replace-task-webpack-plugin

// webpack.config.js
module.exports = {
  // ... other configs
  plugins: [
    new ReplaceTaskWebpackPlugin({
      patterns: [
        {
          match: 'foo',
          replacement: 'bar'
        },
        {
          match: /baz/g,
          replacement: function(){
            return 'bazbaz';
          }
        }
      ]
    })
  ]
};