window.crypto 生成随机数
https://developer.mozilla.org/zh-CN/docs/Web/API/Window/crypto
https://www.cnblogs.com/vickylinj/p/11956434.html
genRandomNumbers = function getRandomNumbers() {
var array = new Uint32Array(10);
window.crypto.getRandomValues(array);
var randText = document.getElementById("myRandText");
randText.innerHTML = "The random numbers are: "
for (var i = 0; i < array.length; i++) {
randText.innerHTML += array[i] + " ";
}
}