js快速排序

<script>
function quickSort(arr){
     if(arr.length<=1){return arr;}
var num=Math.floor(arr.length/2);
var numValue=arr.splice(num,1);
var left = [];
var right = [];
for(var i=0;i<arr.length;i++){
         if(arr[i]<numValue){
    left.push(arr[i]); 
}
else{
    right.push(arr[i]); 
}
     }
return quickSort(left).concat([numValue],quickSort(right));
}
alert(quickSort([7,19,3,10,15,16]));




</script>