New array overwriting global array

Question

I have a global array like:

var myArray = [];

And it has various elements in it. I need to create a new array with the same contents and then reverse it like this:

newArray = myArray;
newArray = newArray.reverse();

However when I do this, it reverses both the myArray and newArray.

What am I doing wrong?

Thanks!

Depends on what you have in array. If it's simple primitive values like numbers, then .slice is enough to clone an array. If you have objects in array, you have to make a deep copy of array, and slice will make only a shallow copy. If it's what you need then use .slice method. — dfsq
– dfsq, Commented Nov 13, 2014 at 6:45

Sampath Liyanage · Accepted Answer · 2014-11-13 06:41:16Z

5

It's because both your arrays are referenced to the same object. To get rid of it you have to clone it with slice..

var myArray = [1,2];
var newArray = myArray.slice(0)
newArray.reverse();

answered Nov 13, 2014 at 6:41

Sampath Liyanage

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