How do I switch between making two variable names be an alias of the same object to making them equal two separate objects?

Question

I have two objects, obj1 and obj2. I want one to have the same properties and values as the other when the user clicks a button, so I write this line:

main.obj1.data=$.extend({},main.someArray[0].data);

But now updating main.obj1.data automatically updates main.someArray[0].data and vice versa. I tested it by checking that this is true with console.logs immediately after that line of code. I thought that this command would clone the objects but not make them aliases of the same object. What am I doing wrong?

I have messy code to sort through before this command...is there anything I might have put in my code before that point which would cause $.extend to no longer work like I think it should?

@Huangism the problem could not be solved by direct assignment, because of object reference. — Ranjit Singh
– Ranjit Singh, Commented Dec 23, 2013 at 22:17

Ranjit Singh · Accepted Answer · 2013-12-23 22:15:54Z

There is two way to solve this

1. main.obj1.data={}; $.extend(main.obj1.data,main.someArray[0].data); 2. main.obj1.data=$.extend(true,{},main.someArray[0].data)

Actually both is doing the same thing You can read more about $.extend()

Jeff Renaud · Accepted Answer · 2013-12-24 13:50:24Z

jQuery extend copy the values so the copied object shouldn't be linked to the initial object. You can verify that in this jsfiddle: http://jsfiddle.net/cFtA7/ (open your console and run the script).

The first parameter in $.extend(true,{},main.someArray[0].data) serve to deep copy your object. If your object has many levels, use this parameter, otherwise, it's not needed.

I'm guessing, but is that possible that your extend code is on a bind object that is called every time you update either one of the values?

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