Re: Should MutationObservers be able to observe work done by the HTML parser?

Re-sending from correct address:

On Fri, Jun 15, 2012 at 4:35 PM, Adam Klein <adamk@google.com> wrote:

> This code alerts in Firefox but not in Chrome:
>
> <!DOCTYPE html>
> <body>
>   <script>
>     var observer = new MutationObserver(function(r) {
>       alert(r);
>     });
>     observer.observe(document.body, {childList: true, subtree: true});
>   </script>
>   <p>Hello, World</p>
> </body>
>
> In WebKit's implementation, we had assumed that MutationObservers were
> meant to observe changes after page load (and I personally thought that
> we'd specced it that way, by putting it in DOM4, not HTML). But it seems
> the Mozilla implementors made a different assumption. But what should
> happen?
>
> IMHO, it may not be worth the gain may not be worth the possible
> performance degradation. If script wants to find out what the parser put on
> the page, it should wait for DOMContentLoaded. But I can imagine a use case
> where script might want to find out about the parser's work during load.
>
> In any case, we should try to come to a decision about this, since this
> seems to be the one major divergence between the existent implementations
> of MutationObservers.
>
> Thoughts?
>
> - Adam
>

Received on Friday, 15 June 2012 23:36:58 UTC