Singleton pattern in RequireJS

Yes this is possible and has its advantage. I use it often for Toolbox-like functions.

This is the basic approach

define(function (require) {
    var singleton = function ()
    {
        return {
            ...
        };
    };
    return singleton();
});

Other approaches that are less ideal but work anyhow

This method uses the "new". It is good, but not needed as you can see in my code above.:  
https://gist.github.com/jasonwyatt/1106973

Some credit for this post goes to ggozad from stackoverflow :
http://stackoverflow.com/questions/9733201/is-it-a-bad-practice-to-use-the-requirejs-module-as-a-singleton