JavaScript 选取 min 到 max 之间的 length 个数字并排序

var randomNumber = function (min, max, length, arr) {    var num = parseInt(Math.random() * max);    if (num < min) {        randomNumber(min, max, length, arr);        return;    }    if (arr.length >= length) {        return arr;    }    arr.push(num);    randomNumber(min, max, length, arr);}

window.onload = function () {    var arr = [];    randomNumber(10, 21, 5, arr);    arr.sort(function (a, b) {        return b - a;    });    console.log(arr);}