Quicksort algorithm: javascript 实现的快速排序算法

qucikSort.js

// var times = 0;

// 快速排序算法
function quickSort(arr) {
    if (!arr || Object.prototype.toString.call(arr).toLowerCase().indexOf('array') < 0) {
        throw new Error('quickSort(): First arguments must be an Array.');
    }
    if (arr.length <= 1) {
        return arr;
    }
    
    var length = arr.length
        , pivotIndex = Math.floor(arr.length / 2)
        , pivot = arr.splice(pivotIndex, 1)[0]
        , left = []
        , right = []
        , i = 0
    
    length -= 1
        
    for (; i < length; i++) {
        if (arr[i] < pivot) {
            left.push(arr[i]);
        } else {
            right.push(arr[i]);
        }
    }
    
    // times ++;
    
    return quickSort(left).concat([pivot], quickSort(right));
}

var arr = [0,2,1,9,3,6,5,7,8,4,2]

console.log(quickSort(arr)); // [0, 1, 2, 2, 3, 4, 5, 6, 7, 8, 9]
// console.log(times); // 7