Question

I have a script that, when a user loads, creates a unique id. Which is then saved in localStorage and used for tracking transactions. Sort of like using a cookie, except since the browser is generating the unique id there might be collisions when sent to the server. Right now I’m using the following code:

function genID() {
    return Math.random().toString(36).substr(2)
        + Math.random().toString(36).substr(2)
        + Math.random().toString(36).substr(2)
        + Math.random().toString(36).substr(2);
}

I realize this is a super basic implementation, and want some feedback on better ways to create a “more random” id that will prevent collisions on the server. Any ideas?

Answer 1

I’ve used this in the past. Collision odds should be very low.

var generateUid = function (separator) {
    /// <summary>
    ///    Creates a unique id for identification purposes.
    /// </summary>
    /// <param name="separator" type="String" optional="true">
    /// The optional separator for grouping the generated segmants: default "-".    
    /// </param>

    var delim = separator || "-";

    function S4() {
        return (((1 + Math.random()) * 0x10000) | 0).toString(16).substring(1);
    }

    return (S4() + S4() + delim + S4() + delim + S4() + delim + S4() + delim + S4() + S4() + S4());
};