[Solved] Why javascript object value is changed? [duplicate]

Question

You are pointing y to the reference of x which itself is pointing to the object {a:1,b:2}.

So in memory it is:

x --> {a:1,b:2}

After you do y = x, it becomes:

y --> x --> {a:1,b:2}

Or to put it simply:

x --> {a:20,b:2}
         ^
         |
y -------

Now when you do y.a = 20, since y and x are both pointing to the same object when properties of the object is changed through either of the references x or y the change will be reflected in both the references:

y --> {a:20,b:2}
        ^
        |
x -------

That is why you get 20,2 when you get x.a.

Accepted Answer