load event can be even attached to the
body element, browsers react differently. For example, Safari, Opera and Chrome will execute the code attached to this event, whereas Firefox and IE won't do nothing. This demo page shows the problem: you should see an alert with the string
Loaded when you first load the page. As you can see, not all browsers display the alert. Everything is due to evaluation of your code during HTML parsing. In fact, browsers parse the document, find your script inside the
body element and then try to execute it. In other words, some browsers think that when everything has been loaded, there's nothing to execute. That could be a problem sometimes.