Quick Sort

example.js

var a = [5,3,7,1,10,-1];
quicksort.call(a);
console.log(a); // -1, 1, 3, 5, 7, 10

quicksort.js

function quicksort(lo, hi){
  var k = Object.keys(this);
  if(typeof lo === 'undefined')lo = k[0];
  if(typeof hi === 'undefined')hi = k[k.length-1];
  if (lo < hi){
    var p = partition.call(this,lo, hi);
    quicksort.call(this, lo, p - 1);
    quicksort.call(this, p + 1, hi);
  }
}
function partition(lo, hi) {
    var pivot = this[hi],j=lo;
    for (i=lo; i < hi;i++) { 
        if (this[i] <= pivot){
            swap.call(this, i, j);
        }
    }
    swap.call(this, i, hi);
    return i;
}

function swap(a,b,c){
  c = this[a];
  this[a] = this[b];
  this[b] = c;
}