Best way to generate unique ids client-side (with Javascript)

Question

I need to generate unique ids in the browser. Currently, I'm using this:

Math.floor(Math.random() * 10000000000000001)

I'd like to use the current UNIX time ((new Date).getTime()), but I'm worried that if two clients generate ids at the exact same time, they wouldn't be unique.

Can I use the current UNIX time (I'd like to because that way ids would store more information)? If not, what's the best way to do this (maybe UNIX time + 2 random digits?)

Answer 1

you can create a GUID using the following links:

http://softwareas.com/guid0-a-javascript-guid-generator

Create GUID / UUID in JavaScript?

This will maximise your chance of "uniqueness."

Alternatively, if it is a secure page, you can concatenate the date/time with the username to prevent multiple simultaneous generated values.

Answer 2

https://github.com/uuidjs/uuid provides RFC compliant UUIDs based on either timestamp or random #'s. Single-file with no dependencies, supports timestamp or random #-based UUIDs, uses native APIs for crypto-quality random numbers if available, plus other goodies.

Answer 3

In modern browser you can use crypto:

var array = new Uint32Array(1);
window.crypto.getRandomValues(array);
console.log(array);