W3C home > Mailing lists > Public > www-dom@w3.org > July to September 2009

Re: Can Dispatch canDispatch()?

From: Sean Hogan <shogun70@westnet.com.au>
Date: Thu, 27 Aug 2009 17:28:09 +1000
Message-ID: <4A963589.5070608@westnet.com.au>
To: Doug Schepers <schepers@w3.org>
CC: DOM mailing list <www-dom@w3.org>
Doug Schepers wrote:
> Hi, Sean-
>
> Sean Hogan wrote (on 8/26/09 8:34 PM):
>> If this method could be implemented reliably then it should be kept. It
>> probably wouldn't be so I suppose it should be dropped.
>>
>> What would count as proper use cases and requirements for the
>> replacement?
>
> The same as with any feature request... any solid explanation of a 
> real-world use that can't already be done via script, and which 
> implementers agree they would support, would serve as a use case.  The 
> requirements would be those things which must be solved, or must be 
> avoided, in designing the feature to solve the use case.
>
>
>> Surely these have already been presented?
>
> Could you elaborate?
>
Actually, I've changed my mind on canDispatch() and I would propose we 
keep it (but maybe change the name to hasEvent() as suggested by Garrett 
Smith.)

*Use cases*

To start this thread Garrett said:

The inability to easily and accurately detect events is a problem.
Programs want to know if an event is implemented at runtime. If it is,
then the feature can be used. If not, it a fallback stratety is in
order. Many new event types are being created and implemented. How can
a program feature-test to see if they are implemented?


This covers every event, but the most relevant events of today would be 
mouseenter, mouseleave and textInput.
These events could be simulated if it is detected that they aren't 
supported natively.


*Current work-arounds*

What events can currently be detected?
Mutation Events can be tested for explicitly on any platform.
I don't know of any way to test for the others using standard APIs.

You can test for many events on HTML elements in today's top browsers. See:
    
http://thinkweb2.com/projects/prototype/detecting-event-support-without-browser-sniffing/

I don't know of any way to test for textInput, but at the moment testing 
for the "TextEvent" module suffices since textInput is the only event in 
that module.

Note that:
- none of these tests are more trustworthy than canDispatch() would be
- these tests only apply to browsers and only to events that may be 
added via inline registration


*Requirements*

- reports whether the implementation will generate trusted events of the 
specified type.
Received on Thursday, 27 August 2009 07:35:43 GMT

This archive was generated by hypermail 2.2.0+W3C-0.50 : Friday, 22 June 2012 06:14:03 GMT