JS 生成UUID

function Id(seed) {
    if (!(this instanceof Id)) {
        return new Id(seed);
    }

    seed = seed || [128, 36, 1];
    this._seed = seed.length ? hat.rack(seed[0], seed[1], seed[2]) : seed;
}
Id.prototype.generateId=function(){
    var res = [], hex = '0123456789ABCDEF';
    for (var i = 0; i < 36; i++) res[i] = Math.floor(Math.random()*0x10);
    res[14] = 4;
    res[19] = (res[19] & 0x3) | 0x8;
    for (var i = 0; i < 36; i++) res[i] = hex[res[i]];
    res[8] = res[13] = res[18] = res[23] = '-';

    return res.join('');
};
var hat  = function (bits, base) {
    if (!base) base = 16;
    if (bits === undefined) bits = 128;
    if (bits <= 0) return '0';

    var digits = Math.log(Math.pow(2, bits)) / Math.log(base);
    for (var i = 2; digits === Infinity; i *= 2) {
        digits = Math.log(Math.pow(2, bits / i)) / Math.log(base) * i;
    }

    var rem = digits - Math.floor(digits);

    var res = '';

    for (var i = 0; i < Math.floor(digits); i++) {
        var x = Math.floor(Math.random() * base).toString(base);
        res = x + res;
    }

    if (rem) {
        var b = Math.pow(base, rem);
        var x = Math.floor(Math.random() * b).toString(base);
        res = x + res;
    }

    var parsed = parseInt(res, base);
    if (parsed !== Infinity && parsed >= Math.pow(2, bits)) {
        return hat(bits, base)
    }
    else return res;
};
hat.rack =function (bits, base, expandBy) {
    var fn = function (data) {
        var iters = 0;
        do {
            if (iters ++ > 10) {
                if (expandBy) bits += expandBy;
                else throw new Error('too many ID collisions, use more bits')
            }

            var id = hat(bits, base);
        } while (Object.hasOwnProperty.call(hats, id));

        hats[id] = data;
        return id;
    };
    var hats = fn.hats = {};

    fn.get = function (id) {
        return fn.hats[id];
    };

    fn.set = function (id, value) {
        fn.hats[id] = value;
        return fn;
    };

    fn.bits = bits || 128;
    fn.base = base || 16;
    return fn;
};

 调用：

var id=Id().generateId()