<pre class="shiki github-dark shaku"><code>function merge(arr, left, right) { let i = 0, j = 0; while(i &lt; left.length &amp;&amp; j &lt; right.length) { if(left[i] &lt; right[j]) { arr[i + j] = left[i]; i++; } else { arr[i + j] = right[j]; j++ } } while(i &lt; left.length) { arr[i + j] = left[i]; i++; } while(j &lt; right.length) { arr[i + j] = right[j]; j++; } return arr;}/** * @param {number[]} arr */function mergeSort(arr) { if (arr.length &lt;= 1) return arr; let mid = arr.length &gt;&gt; 1; let left = mergeSort(arr.slice(0, mid)); let right = mergeSort(arr.slice(mid)); merge(arr, left, right); return arr;}</code></pre>

O(n ㏒ n) - time. O(1) - memory.

Even for Front-End Engineer, it is a must to understand how basic sorting algorithms work. Now you are asked to implement Merge Sort, which sorts an i…