Merge Sort in JavaScript

Introduction

In this lab, we will be exploring the Merge Sort algorithm in JavaScript. Merge Sort is a popular divide-and-conquer sorting algorithm that is efficient and commonly used in practice. By the end of this lab, you will have a solid understanding of how Merge Sort works and how to implement it in your own JavaScript projects.

Merge Sort Algorithm

To practice coding using the merge sort algorithm, follow these steps:

1. Open Terminal/SSH and type node.
2. Use recursion to sort an array of numbers.
3. If the length of the array is less than 2, return the array.
4. Use Math.floor() to calculate the middle point of the array.
5. Use Array.prototype.slice() to slice the array in two and recursively call mergeSort() on the created subarrays.
6. Finally, use Array.from() and Array.prototype.shift() to combine the two sorted subarrays into one.

Here's the code:

const mergeSort = (arr) => {
  if (arr.length < 2) return arr;
  const mid = Math.floor(arr.length / 2);
  const l = mergeSort(arr.slice(0, mid));
  const r = mergeSort(arr.slice(mid, arr.length));
  return Array.from({ length: l.length + r.length }, () => {
    if (!l.length) return r.shift();
    else if (!r.length) return l.shift();
    else return l[0] > r[0] ? r.shift() : l.shift();
  });
};

Try it out with this example:

mergeSort([5, 1, 4, 2, 3]); // [1, 2, 3, 4, 5]

Summary

Congratulations! You have completed the Merge Sort lab. You can practice more labs in LabEx to improve your skills.