SOURCE

// 打乱数组顺序
var shuffle = function (arr) {
    var arrLength = arr.length,
        i = arrLength,
        rndNum;

    /*  while (i--) {
         if (i !== (rndNum = Math.floor(Math.random() * arrLength))) {
             [arr[i], arr[rndNum]] = [arr[rndNum], arr[i]];
         }
     }
     return arr; */
    for (var i = 0, len = arrLength; i < len; i++) {
        var rand = parseInt(Math.random() * len);
        var temp = arr[rand];
        arr[rand] = arr[i];
        arr[i] = temp;
    }
    return arr;

};