Add event listener when window loads I've been using this code for quite some time, but am wondering if there's any improvements I can make to it. Basically it's just code that runs when the page loads or if the code is run after page load, it will run right away. Do you see any cross browser compatibility issues or any more efficient ways of writing this? ol() is a predefined function to be run.

(document.readyState=='complete') ?
  ol():(window.addEventListener&amp;&amp;window.addEventListener("load",ol,false)||
        window.attachEvent&amp;&amp;window.attachEvent("onload",ol));
Just for dealing with ready alone I use jQuery -- it does the cross-browser heavy lifting, is well-tested and maintained. Minified, it's only 32K, and included from a CDN, you get fast delivery that may already be cached in your user's browser.

And there is a lot more code than what you have above to deal with all of the browsers being ready.

There's some good coverage in Paul Irish's 10 Things I learned from the jQuery source screen-case .ready coverage starts around 21:20. There's also some links to jQuery sources.