Iterative quick sort

quicksort-iterative.js

const swap = (arr, i, j) =>  {
  const temp = arr[i]
  arr[i] = arr[j]
  arr[j] = temp;
}

const partition = (arr, start, end) => {
  let pivot = arr[end];
  let low = start;
  
  for(let j = start; j < end; j++){
    if(arr[j] <= pivot){
      swap(arr, low, j);
      low++;
    }
  }
  swap(arr, low, end);
  
  return low;
}

const quickSortIterative = (arr) => {
  let stack = [];
  stack.push({start: 0, end: arr.length - 1});
  
  while(stack.length){
    const { start, end } = stack.shift();   
    const pivotIndex = partition(arr, start, end);  

    if(pivotIndex - 1 > start){
      stack.push({start, end: pivotIndex - 1});
    }
    

    if(pivotIndex + 1 < end){
      stack.push({start: pivotIndex + 1, end});
    }
  }
}

const arr = [2,4,7,1,12,3];
iterativeQuickSort(arr);