Javascript Code To Do Merge Sort

const arr = [3,2,1,4,6,5,7,9,8,10]

const merge = (arr1, arr2) => {
    const results = []
    let i = 0
    let j = 0

    while (i < arr1.length && j < arr2.length) {
        if (arr2[j] > arr1[i]) {
            results.push(arr1[i])
            i++
        } else {
            results.push(arr2[j])
            j++
        }
    }

    while (i < arr1.length) {
        results.push(arr1[i])
        i++
    }

    while (j < arr2.length) {
        results.push(arr2[j])
        j++
    }

    return results
}

const mergeSort = arr => {
    if (arr.length <= 1) return arr
    let mid = Math.floor(arr.length/2)
    let left = mergeSort(arr.slice(0,mid))
    let right = mergeSort(arr.slice(mid))
    return merge(left, right)
}

console.log(mergeSort(arr)) // [1,2,3,4,5,6,7,8,9,10]