Making one array exactly equal to another

Question

I have two arrays:

var array1 = [1, 2, 3];
var array2 = [4, 5, 6];

I want array 1 to be exactly equal to array 2. I've been told I can't simply do:

array1 = array2;

If I can't do this, how can I make array1 equal to array2?

Thanks

Answer 1

If you just need a copy of the elements of an array you can simply use slice like this:

a = [1,2,3]
copyArray = a.slice(0)
[1 , 2 , 3]

As for why you should not use assignement here look at this example:

a = [1,2,3]
b = a 
a.push(99)
a 
[1,2,3,99]
b
[1,2,3,99]

If you copy an array you don't have this problem:

 a = [1,2,3]
 b = a.slice(0)
 a.push(888)
 a 
 [1,2,3,888]
 b 
 [1,2,3]