[whatwg] What should document.write() do when called from setTimeout or event handlers?

Mon Jul 31 19:32:31 PDT 2006

----- Original Message ----- 
From: "Ian Hickson" <ian at hixie.ch>
To: <whatwg at whatwg.org>
Sent: Monday, July 31, 2006 3:34 PM
Subject: [whatwg] What should document.write() do when called from 
setTimeout or event handlers?

>
> I'm trying to spec document.write() and I've run into a difficult edge
> case.
>
> Imagine the server sees this:
>
>   <!DOCTYPE HTML>
>   <html>
>    <head>
>     function test() {
>       document.write('TEST');
>     }
>     setTimeout(test, 1000);
>    </head>
>    <body>
>     <p><img src="test.png" alt="" onload="test()"></p>
>
> ...and then time passes. The image loads, the timeout fires.
>
> Then once the image has loaded and the timer has fired:
>
>    </body>
>   </html>
>
> ...and the connection is closed.
>
> What should happen?
>
> IE seems to make those calls to document.write() simply blow away the
> document, as if the document was closed. Opera seems to do the same.
>
> Mozilla seems to make the document.write() calls insert text into the
> parser, as if they'd been called inline, with the result that the inserted
> text could appear pretty much anywhere. (It's actually a bit more complex
> than that -- it avoids inserting into tokens -- but that's a detail.)
>
> I couldn't work out what Safari and MacIE do; they seem to delay the
> timeout somehow and then print to the end of the page.
>
> Any preferences? I'm particularly interested in feedback from browser
> developers here as to whether there is anything I should know about how
> easy/hard it is to do one thing or the other.
>

(That is what I never understand : why script is allowed to do anything
during load time. Script should start executing when DOM is complete,
when, e.g. getElementById makes real sense.)

>From implementation point of view: all events shall be disabled
until "original DOM complete" state (</html> parsed and processed).
Precisely - events shall be postponed (probably some of them may just
be discarded). First event that shall be fired is window.onload (?)

This is easy to implement and deterministic - read can be implemented
uniformely in all UAs.

Normaly when document.write appears in the <script> section
body of the script has been loaded in full so insertion point for the
write is known - end of the script block.
document.write in other circumstances (event handlers) shall use
end of the body element (?) as an append point.

Andrew Fedoniouk.
http://terrainformatica.com