如何在Javascript中生成32位的随机令牌？

Question

我需要在JavaScript中生成准确的32位随机字母数字字符串。
有直接的功能吗？

Answer 1

使用crypto和类型化数组 ;

function random32bit() {
    let u = new Uint32Array(1);
    window.crypto.getRandomValues(u);
    let str = u[0].toString(16).toUpperCase();
    return '00000000'.slice(str.length) + str;
}

这为我们提供了一个32位的加密随机数，表示为8个字符的零填充字符串（基数为16）

如果要将此扩展为任意数量的char；

function randomHash(nChar) {
    let nBytes = Math.ceil(nChar = (+nChar || 8) / 2);
    let u = new Uint8Array(nBytes);
    window.crypto.getRandomValues(u);
    let zpad = str => '00'.slice(str.length) + str;
    let a = Array.prototype.map.call(u, x => zpad(x.toString(16)));
    let str = a.join('').toUpperCase();
    if (nChar % 2) str = str.slice(1);
    return str;
}

在ES5中，带有注释

function randomHash(nChar) {
    // convert number of characters to number of bytes
    var nBytes = Math.ceil(nChar = (+nChar || 8) / 2);

    // create a typed array of that many bytes
    var u = new Uint8Array(nBytes);

    // populate it wit crypto-random values
    window.crypto.getRandomValues(u);

    // convert it to an Array of Strings (e.g. "01", "AF", ..)
    var zpad = function (str) {
        return '00'.slice(str.length) + str
    };
    var a = Array.prototype.map.call(u, function (x) {
        return zpad(x.toString(16))
    });

    // Array of String to String
    var str = a.join('').toUpperCase();
    // and snip off the excess digit if we want an odd number
    if (nChar % 2) str = str.slice(1);

    // return what we made
    return str;
}