编辑代码

const merge = (left, right) => {
    let arr = []
    while(left.length && right.length) {
        if(left[0] < right[0]) {
            arr.push(left.shift())
        } else {
            arr.push(right.shift())
        }
    }
    return [...arr, ...left, ...right]
}
function mergeSort(arr) {
    let half = Math.floor(arr.length / 2)
    if(arr.length < 2) return arr
    let left = arr.splice(0, half)
    console.log(left)
    return merge(mergeSort(left), mergeSort(arr))
}

console.log(mergeSort([6,3,1,4,6,7,21,3,1,68]))