[Javascript] Onload event handlers for Safari

[nick at nickfitz.co.uk (Nick Fitzsimons)]

On 29 Aug 2006, at 16:46, Guillaume wrote:

> I've come across this link apparently solving a long time problem  
> with onload event handlers for Safari...
>
> Reading articles about the onload event handlers for Safari, it  
> seems this browser behaves differently than Ie and Mozilla...
> Here's a ressource that might help us on Den Edwards's site in an  
> article called: window.onload (again)
> http://dean.edwards.name/weblog/2006/06/again/
>

Safari handles onload perfectly well. Dean's article is about a  
different problem: the fact that, in _all_ browsers, onload only  
fires after all of the contents of the page have loaded. This means  
that, if (for example) you have images on a page, the onload event  
only fires when all of the images have been downloaded, which can  
take a while if there are lots of them, they are very large, or the  
user is on a slow connection.

If you are using unobtrusive JavaScript to attach event handlers to  
elements on the page when the onload event fires, it is thus possible  
that the user will try to interact with the page before the onload  
event has fired, which is before your user interface has been activated.

What Dean's (and others') technique does is allow one to start one's  
script when the page has been _parsed_ into a DOM, which is not the  
same thing as when it has _loaded_. This means that (assuming you  
don't try to do too much) you can get all your initialisation in  
place before the page is displayed to the user, and long before the  
onload event fires.

It's a useful technique which handles one of the most important  
problems in DOM scripting (in fact, we discussed it at some length  
over a year ago at a get-together in London [1] which led to the  
founding of the Web Standards Project's DOM Scripting Task Force  
[2]). But it shouldn't be confused with onload event handling,  
despite Dean's title; it's to do with the DOMContentLoaded event, to  
use the Mozilla name for it, and how that can be emulated in IE and  
Safari.

Footnotes:
[1] <http://www.nickfitz.co.uk/2005/06/13/javascript-get-together- 
london-2005-06-11/>
[2] <http://webstandards.org/action/dstf/>

Cheers,

Nick.
-- 
Nick Fitzsimons
http://www.nickfitz.co.uk/