My Merge-Sort Implementation

cyclone-merge-sort.js

const testArray1 = [3, 2, 1, 13, 8, 5, 0, 1];
const testArray2 = [105, 79, 100, 110, 3];

function merge(leftHalfOfArray, rightHalfOfArray) {
  let mergedArray = [];

  let leftHalfPointer = 0;
  let rightHalfPointer = 0;
  let mergedPointer = 0;

  while (
    leftHalfPointer < leftHalfOfArray.length &&
    rightHalfPointer < rightHalfOfArray.length
  ) {
    if (leftHalfOfArray[leftHalfPointer] < rightHalfOfArray[rightHalfPointer]) {
      mergedArray[mergedPointer++] = leftHalfOfArray[leftHalfPointer++];
    } else {
      mergedArray[mergedPointer++] = rightHalfOfArray[rightHalfPointer++];
    }
  }

  for (leftHalfPointer; leftHalfPointer < leftHalfOfArray.length; leftHalfPointer++) {
    mergedArray[mergedPointer++] = leftHalfOfArray[leftHalfPointer];
  }

  for (rightHalfPointer; rightHalfPointer < rightHalfOfArray.length; rightHalfPointer++) {
    mergedArray[mergedPointer++] = rightHalfOfArray[rightHalfPointer];
  }

  return mergedArray;
}

function mergeSort(array) {
  if (array.length < 2) {
    return array;
  }
  
  let arrayLength = array.length;
  let middleIndex = Math.floor(arrayLength / 2);
  let nextLeftHalfOfArray = mergeSort(array.slice(0, middleIndex));
  let nextRightHalfOfArray = mergeSort(array.slice(middleIndex));

  return merge(nextLeftHalfOfArray, nextRightHalfOfArray);
}

console.log(mergeSort(testArray1));
console.log(mergeSort(testArray2));