SOURCE

		var obj={
            userNeme:"xiaoming",
            age:20,
            obj2:{
                email:"54648468@qq.com"
            },
            ignore:undefined,
            ignoreFunction(){
                console.log(345);
            }
		}
        var obj1 = JSON.parse(JSON.stringify(obj))//会忽略掉对象obj里面的undefined和函数
        obj.phone=12356564;
        obj.obj2.address="河南";
        console.log(obj);//{userNeme: "xiaoming", age: 20, obj2: {email: "54648468@qq.com", address: "河南"}, ignore: undefined, ignoreFunction: ƒ, …}
        console.log(obj1);//{userNeme: "xiaoming", age: 20, obj2: {email: "54648468@qq.com"}}