Heap, max heap and heap sort,merge and quck sort

abitrefactoring.js

function heapify(arr, i) {
  let [index, left, right] = [i, i*2+1, i*2+2]
  if(arr[left] && arr[left] > arr[i]) {
    index = left
  }
  if(arr[right] && arr[right] > arr[index]) {
    index = right
  }
  if(index !== i) {
    let temp = arr[i]
    arr[i] = arr[index]
    arr[index] = temp
    heapify(arr, index)
  }
}

function heapsort(arr) {
  for(i=0; i<=arr.length/2; i++) {
    heapify(arr, i)
  }
  let new_array = []
  while(arr.length) {
    let temp = arr[0]
    arr[0] = arr[arr.length -1]
    arr[arr.length-1] = temp
    new_array.unshift(arr.pop())
    heapify(arr, 0)
  }
  return new_array
}

heapsort([11,55,99,88,900,100,2,5,6,18,12])

heapsort.js

function heapify(arr, i) {
  let index = i
  let left = index*2 + 1
  let right = index*2 + 2

  if(arr[left] > arr[index]) {
    index = left
  }
  if(arr[right] > arr[index]) {
    index = right
  }
  if(index != i) {
    let temp = arr[i]
    arr[i] = arr[index]
    arr[index] = temp
    heapify(arr, index)
  }
  return arr
}

function heapsort(arr) {
  let i = Math.floor(arr.length/2 - 1)
  while(i>-1) {
    heapify(arr, i)
    i--
  }
let new_array = []
  while(arr.length) {
    let temp = arr[0]
    arr[0] = arr[arr.length - 1]
    arr[arr.length-1] = temp
    new_array.unshift(arr.pop())
    heapify(arr, 0)

  }
  return new_array
}

experiment = [6, 5, 3, 1, 8, 7, 2, 4]

heapsort(experiment)

mergesort.js

var a = [34, 203, 3, 746, 200, 984, 198, 764, 9];
 
function mergeSort(arr)
{
    if (arr.length < 2)
        return arr;
 
    var middle = Math.floor(arr.length / 2);
    var left   = arr.slice(0, middle);
    var right  = arr.slice(middle, arr.length);
 
    return merge(mergeSort(left), mergeSort(right));
}
 
function merge(left, right)
{
    var result = [];
 
    while (left.length && right.length) {
        if (left[0] <= right[0]) {
            result.push(left.shift());
        } else {
            result.push(right.shift());
        }
    }
 
    while (left.length)
        result.push(left.shift());
 
    while (right.length)
        result.push(right.shift());
 
    return result;
}

quicksort.js

function quicksort(arr) {
  if(arr.length === 0) {
    return arr
  }
  elm = arr[0]
  return [].concat(arr.filter(x => x < elm)).concat(elm).concat(arr.fliter(x => x > elm))
}