//1. 经典洗牌算法实现
function shuffle(array) {
let arrayLength = array.length,
randomIndex, //随机数
tempItem; //临时存储元素
for (let i = arrayLength - 1; i >= 0; i--) {
randomIndex = Math.floor(Math.random() * (i + 1));
tempItem = array[randomIndex];
array[randomIndex] = array[i];
array[i] = tempItem;
}
return array;