Javascript Algorithm Array Sort Heap Sort 2

/**//from   w w  w  .jav a2  s. co m
 * Swap the i-th element with the j-th element of the array a
 * @param  {Array}   a the array
 * @param  {Int}   i first index
 * @param  {Int}   j second index
 * @return {Array}
 */
function swap(a,i,j){
  var tmp = a[i];
  a[i] = a[j];
  a[j] = tmp;
  return a;
}

/**
 * Restore the max-heap property on the i-th element
 * @param  {Array}  a    the array
 * @param  {Int}   i    index of the element 
 * @param  {Int}  size size of the heap
 * @return {Array}  
 */
function maxHeapify(a,i,size){
  var l = (2*i)+1;  /* left child index */
  var r = (2*i)+2;  /* right child index */
  var largest = i;  /* largest element index */

  /* check if left child is greater than parent */
  if( l<size && a[l]>a[i] ){
    largest = l;
  }

  /* check if right child is greater than the largest between parent and left child */
  if( r<size && a[r]>a[largest] ){
    largest = r;
  }

  /* swap elements if necessary and call maxHeapify on largest element */
  if( i !== largest ){
    a = swap(a,i,largest);
    a = maxHeapify(a,largest,size);
  }

  return a;
}

/**
 * Given the a array, return a max-heap
 * @param  {Array} a input array
 * @return {Array} max-heapified array
 */
function buildMaxHeap(a){
  var i = 0;
  var l = a.length;
  for( i=Math.floor(l/2); i>=0; i-=1 ){
    a = maxHeapify(a,i,l);
  }
  return a;

}

/**
 * Sort the given array using Heapsort algorithm
 * @param  {Array} a
 * @return {Array} sorted array
 */
function heapsort(a){
  var i = 0;
  /* size of the sub-array that is not been "max-heapified" yet;
   * initially is equal to the array size */
  var l = a.length-1;  
  a = buildMaxHeap(a);
  for( i=l; i>0; i-=1 ){
    a = swap(a,0,i);
    l -=1;
    a = maxHeapify(a,0,l);
  }

  return a;

}

var arr = [55,13,41,124,-1,0,5];

console.log( heapsort(arr) );