Javascript implementation of Heap's Algorithm for combinatorics

combinatorics.js

//http://stackoverflow.com/questions/872310/javascript-swap-array-elements
Array.prototype.swap = function (x,y) {
  var b = this[x];
  this[x] = this[y];
  this[y] = b;
  return this;
}

//https://en.wikipedia.org/wiki/Heap's_algorithm
function generate(n){
	var combinations = [];
	var A = [];
    var c = [];
    for(var i = 0; i < n; i++){
        c.push(0);
		A.push(i+1);
    }
    combinations.push(A);
    i = 0;
    while(i < n){
        if(c[i] < i){
            if(i % 2 == 0){
                A.swap(0, i);
            }else{
                A.swap(c[i], i);
            }
            combinations.push(A);
            c[i]++;
            i = 0;
        }else{
            c[i] = 0;
            i++;
        }
    }
  return combinations;
}