Necromancing.
Effectively, a Guid, or UUID as it is called in non-microsoft-circles, is just a 128-Bit cryptographic random number, with the uuid version number (1-5) being at a fixed location byte.
So when you just generate a bunch of random numbers betwween 0 and 65535 and hex-encode them, like this:
function guid()
{
function s4()
{
return Math.floor(Math.random() * 65536).toString(16).padStart(4, '0')
} // End Function s4
return s4() + s4() + '-' + s4() + '-' + "4" + s4().substr(1) + '-' + s4() + '-' + s4() + s4() + s4();
} // End Function guid
you get a valid GUID, but due to the random-implementation, it's not cryptographically secure.
To generate a cryptographically secure GUID, you need to use window.crypto (or window.msCrypto for Internet Exploder).
That goes like this:
function cryptGuid()
{
var array = new Uint16Array(8);
(window.crypto || window.msCrypto).getRandomValues(array);
var dataView = new DataView(array.buffer);
var parts = [];
for(var i = 0; i < array.length; ++i)
{
// 0&1,2,3,4,5-7 dataView.getUint16(0-7)
if(i>1 && i<6) parts.push("-");
parts.push(dataView.getUint16(i).toString(16).padStart(4, '0'));
}
parts[5] = "4" + parts[5].substr(1);
// console.log(parts);
return parts.join('').toUpperCase();// .toLowerCase();
}
cryptGuid();
Plus you have to decide, if you return the number as lower-or upper-case character string. Certain software require lowercase characters (e.g. Reporting Service), while others generate uppercase characters (SQL-Server).