How to duplicate elements in a js array?

Question

Whats the easiest way (with \"native\" javascript) to duplicate every element in a javascript array?

The order matters.

For example:

Answer 1

how 'bout that?

for (i=a.length-1;i>=0;i--)a.splice(i,0,a[i]);

iterating backwards is undervalued, in this case it keeps the index intact ;)