[whatwg] readystatechange for SCRIPT (Re: Feedback regarding script execution)

Simon Pieters simonp at opera.com
Thu Sep 8 14:24:51 PDT 2011

On Thu, 08 Sep 2011 23:15:48 +0200, Ian Hickson <ian at hixie.ch> wrote:

> On Thu, 8 Sep 2011, Boris Zbarsky wrote:
>> On 9/8/11 4:41 PM, Hallvord R. M. Steen wrote:
>> > as far as I know Opera is currently the only browser that supports
>> > both script.onload and script.onreadystatechange, and this is causing
>> > us compatibility problems because many scripts set both and expect
>> > only one of them to run. For this reason, we plan to drop
>> > script.onreadystatechange support.
>> That will break still other sites.  That's why it's been added to the
>> spec; it turned out that as long as script.onreadystatechange is not
>> undefined (which the spec currently requires because it defines all on*
>> attributes on all elements) there are sites that expect the event to be
>> fired.  Where by "sites" I mean at least Yandex maps so far in Gecko's
>> experience of shipping this for a few weeks in nightlies.
>> The other obvious option here is to move onreadystatechange from being
>> on all elements to only being on some elements....
> Yeah, that is rapidly becoming my conclusion too. A few exceptions like
> this aren't going to kill us (per spec <marquee> already has a few
> exceptions of its own), but I would like to keep it to a minimum if we at
> all can. Having just one set of these event handlers that apply  
> everywhere
> simplifies the platform quite a bit.

For implementors, yes, but it's not really helpful for authors. For  
authors it would be more helpful to be able to detect if an event is  
supported on a particular element (or document or window) by checking if  
the event handler is supported. Currently if we introduce a new event on  
an element that has the same name as an event used elsewhere, authors  
can't feature detect support for the new event.

> I'd like to study some of the pages that break if they have both, though,
> to see if there's anything simpler we can do first.

Simon Pieters
Opera Software

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