javascript sort sparse array keep indexes

Question

What is the best method to sort a sparse array and keep the elements on the same indexes? For example:

a[0] = 3, 
a[1] = 2, 
a[2] = 6,
a[7] = 4,
a[8] = 5,
         


        

Answer 1

var arr = [1,2,3,4,5,6,7,8,9,10];
// functions sort
function sIncrease(i, ii) { // ascending
 if (i > ii)
 return 1;
 else if (i < ii)
 return -1;
 else
 return 0;
}
function sDecrease(i, ii) { //descending
 if (i > ii)
 return -1;
 else if (i < ii)
 return 1;
 else
 return 0;
}
function sRand() { // random
 return Math.random() > 0.5 ? 1 : -1;
}
arr.sort(sIncrease); // return [1,2,3,4,5,6,7,8,9,10]
arr.sort(sDecrease); // return [10,9,8,7,6,5,4,3,2,1]
arr.sort(sRand); // return random array for examle [1,10,3,4,8,6,9,2,7,5]