[JS] Heap sort

heapSort.js

function heapSort(array) {
  const heap = heapify(array);
  let lengthToConsider = array.length;
  for(let i = array.length - 1; i > 0; i--) {
    swap(array, i, 0); 
    lengthToConsider--;
    descendHeap(array, lengthToConsider, 0);
  }
}

function heapify(array) {
  const nOfElements = array.length;
  const halfHeapIndex = Math.floor(nOfElements / 2) - 1;
  for(let i = halfHeapIndex; i <= 0; i--) {
    descendHeap(array, nOfElements, i);
  }   
}

function descendHeap(array, arrayLength, indexToDescend) {
  const leftIndex = 2 * indexToDescend + 1;
  const rightIndex = 2 * indexToDescend + 2;
  
  let maxIndex = indexToDescend;
  if(leftIndex < arrayLength && array[leftIndex] > array[maxIndex]){
    maxIndex = leftIndex;
  }    
  if(rightIndex < arrayLength && array[rightIndex] > array[maxIndex]){
    maxIndex = rightIndex;
  } 
  if(maxIndex != indexToDescend) {
    swap(array, indexToDescend, maxIndex);
    descendHeap(array, arrayLength, maxIndex);
  }
}

function swap(array, i, j) {
  const aux = array[i];
  array[i] = array[j];
  array[j] = aux;
}

// -------------------------- Test -----------------------------------------//
const array = [51, 46, 17, 34, 41, 15, 14, 23, 30, 21, 10, 12]
heapSort(array);
console.log(array); // [10, 12, 14, 15, 17, 21, 23, 30, 34, 41, 46, 51]