HeapSortV2.js

let arrayLength = 0

/* to create MAX array */

function heapRoot (input, i) {
 const left = 2 * i + 1
 const right = 2 * i + 2
 let max = i

 if (left < arrayLength && input[left] > input[max]) {
 max = left
 }

 if (right < arrayLength && input[right] > input[max]) {
 max = right
 }

 if (max !== i) {
 swap(input, i, max)
 heapRoot(input, max)
 }
}

function swap (input, indexA, indexB) {
 [input[indexA], input[indexB]] = [input[indexB], input[indexA]]
}

export function heapSort (input) {
 arrayLength = input.length

 for (let i = Math.floor(arrayLength / 2); i >= 0; i -= 1) {
 heapRoot(input, i)
 }

 for (let i = input.length - 1; i > 0; i--) {
 swap(input, 0, i)
 arrayLength--

 heapRoot(input, 0)
 }
 return input
}