实现js中所有对象的深度克隆（包装对象，Date对象，正则

var clone = function (obj) {

___if(obj === null) return null

___if(typeof obj !== 'object') return obj;

___if(obj.constructor===Date) return new Date(obj);

___if(obj.constructor === RegExp) return new RegExp(obj);

___var newObj = new obj.constructor (); //保持继承链

___for (var key in obj) {

______if (obj.hasOwnProperty(key)) { //不遍历其原型链上的属性

_________var val = obj[key];

_________newObj[key] = typeof val === 'object' ? arguments.callee(val) : val; // 使用arguments.callee解除与函数名的耦合

______}

___}

___return newObj;

};