JS快速排序算法實現

function quickSort(arr){
  if(arr.length == 0){
    return [];
  }
  var left = [];
  var right = [];
  var selectItem = arr[0];
  for(var i = 1; i < arr.length; i++){
    if(arr[i] < selectItem){
      left.push(arr[i]);
    } else{
      right.push(arr[i]);
    }
  }
  return quickSort(left).concat(selectItem, quickSort(right));
}