index.js

var lut = [];

for (var i = 0; i < 256; i++) {
    lut[i] = (i < 16 ? '0' : '' ) + (i).toString(16);
}

/**
* Fast UUID generator, RFC4122 version 4 compliant.
* @author Jeff Ward (jcward.com).
* @license MIT license
* @link http://stackoverflow.com/questions/105034/how-to-create-a-guid-uuid-in-javascript/21963136#21963136
**/
function guidV4() {
    var d0 = Math.random()*0xffffffff|0;
    var d1 = Math.random()*0xffffffff|0;
    var d2 = Math.random()*0xffffffff|0;
    var d3 = Math.random()*0xffffffff|0;

    return lut[d0&0xff] + lut[d0>>8&0xff] + lut[d0>>16&0xff] + lut[d0>>24&0xff] +
        '-' +lut[d1&0xff] + lut[d1>>8&0xff] +
        '-' + lut[d1>>16&0x0f|0x40] + lut[d1>>24&0xff] +
        '-' + lut[d2&0x3f|0x80] + lut[d2>>8&0xff] +
        '-' + lut[d2>>16&0xff] + lut[d2>>24&0xff] + lut[d3&0xff] + lut[d3>>8&0xff] + lut[d3>>16&0xff] + lut[d3>>24&0xff];
}

function genToken(isShort) {
    var d0 = Math.random()*0xffffffff|0;
    var d1 = Math.random()*0xffffffff|0;

    var short = lut[d0>>16&0xff] + lut[d0>>24&0xff] + lut[d1&0xff] + lut[d1>>8&0xff];

    return isShort ? short : short + lut[d1>>16&0xff] + lut[d1>>24&0xff];
}

module.exports = {
    v4: guidV4,
    token: genToken
};