显式演员语法

Question

下面两行代码有什么区别？在功能上，我认为它们是相同的，但是是否有某种情况或最佳实践会决定我应该使用哪一种？

var fs = require('fs');

var nodeModules = {};
fs.readdirSync('node_modules')
  .filter(function(x) {
    return ['.bin'].indexOf(x) === -1;
  })
  .forEach(function(mod) {
    nodeModules[mod] = 'commonjs ' + mod;
  });



module.exports = {
  entry: [
    './server.js'
  ],
  target: 'node',
  output: {
    path: __dirname,
    publicPath: '/',
    filename: 'bundle.js'
  },
  externals: nodeModules,
  module: {
    loaders: [{
      exclude: /node_modules/,
      loader: 'babel',
      query: {
        presets: ['react', 'es2015', 'stage-1']
      }
    }]
  },
  resolve: {
    extensions: ['', '.js', '.jsx']
  },
  devServer: {
    historyApiFallback: true,
    contentBase: './'
  }
};