js实现快速排序

function quickSort (arr) {
    if (arr.length <= 1) {
        return arr;
    }
    var mid = Math.floor(arr.length/2);
    var midValue = arr.splice(mid,1);
    var left = [];
    var right = [];

    for (var i=0;i<arr.length;i++){
        if (arr[i]<midValue) {
        left.push(arr[i]);
        }else {
            right.push(arr[i]);    
        }
        }
    return quickSort(left).concat([midValue],quickSort(right));
}
alert(quickSort([12,5,37,6,22,40,4,5,6,45,84,48]));    

1.找一个基准点

2.建立两个数组，分别存储左边和右边的数组

3.利用递归进行下次比较