function merge(leftArr, rightArr) { let leftInd = 0, rightInd = 0; const sortedArr = []; while(leftInd < leftArr.length && rightInd < rightArr.length) { if (leftArr[leftInd] < rightArr[rightInd]) { sortedArr.push(leftArr[leftInd]); leftInd++; } else { sortedArr.push(rightArr[rightInd]); rightInd++; } } // join leftover values from left array or right array return sortedArr.concat(leftArr.slice(leftInd)).concat(rightArr.slice(rightInd)); } const mergeSort = (arr) => { if (arr.length <= 1) { return arr; } const mid = Math.floor(arr.length / 2); const leftArr = mergeSort(arr.slice(0, mid)); const rightArr = mergeSort(arr.slice(mid)); return merge(leftArr, rightArr); }; console.log(mergeSort([4,12,5,3,78,12,133,32, 1000, 4000])); console.log(mergeSort([14, 1, 10, 2, 3, 5, 6, 4, 7, 11, 12, 13])); console.log(mergeSort([])); console.log(mergeSort([1])); console.log(mergeSort([2, 1])); console.log(mergeSort([1,7,2,3,4,1,10,2,3,4,5])); console.log(mergeSort(["One Piece", "One-Punch Man", "My Hero Academia", "Jujutsu Kaisen", "Death Note", "Fullmetal Alchemist: Brotherhood", "Akame ga Kill", "Bleach", "Black Clover"])); module.exports.mergeSort = mergeSort;