快速排序？

function quickSort (arr) {
  if (arr.length < 2) return arr
  var middle = Math.floor(arr.length / 2)
  var flag = arr.splice(middle, 1)[0]
  var left = [],
        right = []
  for (var i = 0; i < arr.length; i++) {
    if (arr[i] < flag) {
      left.push(arr[i])
    } else {
      right.push(arr[i])
    }
  }
  return quickSort(left).concat([flag], quickSort(right))
}