JS - 数据类型的值拷贝函数（深拷贝）

function mottoClone (obj) {
  if (obj === null || typeof obj !== 'object') return obj;
  if (obj instanceof Boolean) return new Boolean(obj.valueOf());
  if (obj instanceof Number) return new Number(obj.valueOf());
  if (obj instanceof String) return new String(obj.valueOf());
  if (obj instanceof RegExp) return new RegExp(obj.valueOf());
  if (obj instanceof Date) return new Date(obj.valueOf());
  var cpObj = obj instanceof Array ? [] : {};
  for (var key in obj) cpObj[key] = myClone(obj[key]);
  return cpObj;
}

支持的数据类型或格式有：Boolean,Number,String,RegExp,Date,Function,Array,JSON
支持深拷贝（循环迭代），如：
var obj = {
  id: 1,
  name: 'xxx',
  sayName: function () {
    console.log('my name is' + this.name);
  },
  childs: [
    {}, 
    {}, 
    ...
  ],
  opts: {
    xxx: [],
    ...
  },
  ...
};
var newObj = mottoClone(obj);