在JavaScript中修改原始对象

Question

I have define an object in variable "c". I have also make a function in which I passed a object. When I do changes in that variable it is also changing original object but my concern is why below given statement is not working with that object. fiddle

function changeParam(x, y, z) {
  x = 3;
  y = "new string";
  z["key2"] = "new";
  z["key3"] = "newer";

  z = {"new" : "object"};
}

var a = 1,
    b = "something",
    c = {"key1" : "whatever", "key2" : "original value"};
var m=c;
changeParam(a, b, c);

console.log(c)
console.log(m)

Answer 1

JavaScript passes object by reference. To pass it by value you need to clone it before.

In this question you'll find options of doing it. There are a lot ways of doing it, each with advantages and disadvantages. Depends on what you want from your object you can choose one.

Shortest way is to stringify object to JSON and parse again. (note that you can not save function in such object):

var newObject = JSON.parse(JSON.stringify(oldObject));

Works well with your jsfiddle

If you are using jquery in your project, you could use "jquery way" as well:

var newObject =  jQuery.extend(true, {}, oldObject);