Does null occupy memory in javascript?

Question

I\'ve got the following situation:

var large = [a,b,c,d,e,f,g,h,i];
var small = [a2, b2, c2, null, null, null, null, null, null, i2];

where

Answer 1

Why not just put the small items into large[2].small? Anyway, you usually don't have to worry about memory consumption in javascript, but still it is better to leave the unused positions in small undefined (which is something else than setting them to undefined!), so that javascript engine can decide to switch to sparse array (represented by a hashtable instead of an array).