如何从数组中随机获取n个元素

尝试以下无损快速功能：

function getRandom(arr, n) {    var result = new Array(n),        len = arr.length,        taken = new Array(len);    if (n > len)        throw new RangeError("getRandom: more elements taken than available");    while (n--) {        var x = Math.floor(Math.random() * len);        result[n] = arr[x in taken ? taken[x] : x];        taken[x] = --len in taken ? taken[len] : len;    }    return result;}