1  'use strict'
 2  
 3  module.exports = clone
 4  
 5  var getPrototypeOf = Object.getPrototypeOf || function (obj) {
 6    return obj.__proto__
 7  }
 8  
 9  function clone (obj) {
10    if (obj === null || typeof obj !== 'object')
11      return obj
12  
13    if (obj instanceof Object)
14      var copy = { __proto__: getPrototypeOf(obj) }
15    else
16      var copy = Object.create(null)
17  
18    Object.getOwnPropertyNames(obj).forEach(function (key) {
19      Object.defineProperty(copy, key, Object.getOwnPropertyDescriptor(obj, key))
20    })
21  
22    return copy
23  }