Starting a javascript code on page load

Hello again, I have been setting up a javascript marquee code to work in a widget I am trying to build for my site, and I almost have it except for on small problem I am having.

The marquee does not start scrolling on every page load, it is kinda hit or miss.

I found this code in the script which I beleive is suppose to start the marquee on page load but I don't think it is catching the user's updates and every page load in elgg.

           if (window.addEventListener)
           window.addEventListener("load", initializemarquee, false)
           else if (window.attachEvent)
           window.attachEvent("onload", initializemarquee)
           else if (document.getElementById)
           window.onload=initializemarquee

Could someone point me in the right direction on choosing the best way to start this script?

Thanks a bunch