Heap sort in js

heapsort.js

function maxHeapify(arr, i) {
    const l = i * 2 + 1;
    const r = i * 2 + 2;
    let largest;
    if (l <= arr.heapSize && arr[l] > arr[i]) {
        largest = l;
    } else largest = i;
    if (r <= arr.heapSize && arr[r] > arr[largest]) {
        largest = r;
    } 
    if (largest != i) {
        let temp = arr[i];
        arr[i] = arr[largest];
        arr[largest] = temp;
        maxHeapify(arr, largest);
    }
}

function buildMaxHeap(arr) {
    arr.heapSize = arr.length - 1;
    for (let i = parseInt((arr.length - 2)/2); i >= 0; i--) {
        maxHeapify(arr, i);
    }
}

function heapSort(arr) {
    buildMaxHeap(arr);
    for (let i = arr.length - 1; i >= 1; i--) {
        let temp = arr[0];
        arr[0] = arr[i];
        arr[i] = temp;
        arr.heapSize = arr.heapSize - 1;
        maxHeapify(arr, 0);
    }
    return arr;
}