function clone(o) {
    var temp = {}
    for (var key in o) {
        if (typeof o[key] == 'object') {
            temp[key] = clone(o[key])
        } else {
            temp[key] = o[key]
        }
    }
    return temp
}

测试：

var obj = {qwe:123,asd:456};
var obj1 = obj,obj2 = clone(obj);
obj1.qwe = 456;
obj2.asd = 'asdzxc';
console.log(obj);//{qwe: 456, asd: 456}
console.log(obj1);//{qwe: 456, asd: 456}
console.log(obj2);//{qwe: 123, asd: "asdzxc"}