Trigger an overlay via JS

[Dasfaust]

How would one go about triggering an overlay with Javascript? I could only find one post on this subject, and this is what I've got so far:

var $trigger = window.onload;
var $templateHtml = "test";
XenForo.createOverlay($trigger, $templateHtml).load();

But I'm getting this error:

Uncaught TypeError: Cannot call method 'refresh' of null xenforo.js:191
    c.extend.activate xenforo.js:191
    jQuery.fn.extend.xfActivate xenforo.js:177
    c.extend.createOverlay xenforo.js:199
    (anonymous function)

Am I going about this right?

 

[Jake Bunce]

http://xenforo.com/community/threads/xenforo-ajax-tutorial.8091/