如何使用原生 Javascript 代码深度克隆一个对象

var s = {"a": "aaaaa"},
lightClone = {},
deepClone = {};
//浅clone
lightClone = s;
lightClone.a = 'lightClone';
console.log(lightClone.a);//lightClone
console.log(s.a);//lightClone
//深clone
s = {"a": "aaaa"};
for(var k in s) {
    deepClone[k] = s[k]; 
}
deepClone.a = "deepClone";
console.log(deepClone.a);//deepClone
console.log(s.a);//aaaaa