Javascript function, objects

Question

I got an object defined global way:

window.myobj = {};

Then new elements are being added and finally it is being saved via ajax to database by SaveData(obj) function. The problem is, that I am making it alot of times in short period, and it seems that what is being passed to function is only a pointer to one single object, so when another event occures, it changes inside a save function even when it was changed outside. In PHP, you have to use &$obj for it... so how do I do it properly, so the obj passed to the function would not be only a pointer?

Edit: The problem appeared in here:

Lets say that event = {time:123,type:blah}

function SaveData(event){
  obj = jQuery.extend({}, event); // doesn't seem to replicate event
  $.post('save',obj,function(res){
    if(res) console.log(obj);
  });
  if(obj.type == 'blah'){
     newobj = jQuery.extend({}, obj);
     newobj.type = 'newtype';
     newobj.time = 234;
     SaveData(newobj);
  }else if(obj.type == 'newtype'){
     newobj = jQuery.extend({}, obj);
     newobj.type = 'lasttype';
     newobj.time = 345;
     SaveData(newobj);  
  }
}

This returns 3 objects that are the same:

{time:345,type:lasttype}

Could you post more of your code so that we know how you access / pass around the object? — Felix Kling, Sep 17 '13 at 08:38
What function? Why is it relevant? The object is already global, what's the point passing it around to functions? Sorry, but your question is very unclear. — Shadow The GPT Wizard, Sep 17 '13 at 08:38
http://stackoverflow.com/questions/122102/most-efficient-way-to-clone-an-object — Slavo, Sep 17 '13 at 08:53
The weird thing is that it does save different objects, but writes the same... — Flash Thunder, Sep 17 '13 at 09:13
Because `obj` is global and at the moment you are calling `console.log(obj)`, you are getting the value of `obj` from the last call to `SaveData`. However, when you pass the object to `$.post`, it gets evaluated immediately. It doesn't seem that `obj` must be global anyways. Just make it local. — Felix Kling, Sep 17 '13 at 09:17
Oh! because `obj = ''` in function makes it global, and `var obj = ''` makes it local! Good to know that... — Flash Thunder, Sep 17 '13 at 09:21

score 0 · Answer 1 · answered Sep 17 '13 at 08:42

Assuming your Object myobj does not contain any functions, but only values and further objects, one very easy way to clone the Object (and thus get rid of the problem with pointers) would be:

var clonedObj = JSON.parse(JSON.stringify(window.myobj));

Now you can pass the clonedObj to your SaveData Function.

score 0 · Answer 2 · answered Sep 17 '13 at 08:53

0

If you're using jQuery, the answer is as simple as;

var myCopy = $.extend(true, {}, window.myobj);

If not, this function will create a deep copy the object - including functions and nested objects;

function clone(original) {

    if (original == null || typeof(original) !== 'object')
        return original;

    var theClone = original.constructor.call(this);

    for (var property in original) {
        theClone[property] = clone(original[property]);
    }

    return theClone;

}

answered Sep 17 '13 at 08:53

Björn

29,019
9
65
81

@FlashThunder - you'd want to pass in `true` as first parameter to extend, to create a deep copy, depending on your objects. – Björn Sep 17 '13 at 08:59
it is simple 2d object... but the problem is that it doesn't seem to work at all, still refers to the same object, as in given example... – Flash Thunder Sep 17 '13 at 09:03

Javascript function, objects

2 Answers2