W3C home > Mailing lists > Public > www-svg@w3.org > January 2005

Re: DOM Level 3 events

From: Boris Zbarsky <bzbarsky@MIT.EDU>
Date: Tue, 18 Jan 2005 18:56:44 -0600
Message-ID: <41EDB04C.5090606@mit.edu>
To: Peter Sorotokin <psorotok@adobe.com>
CC: Jon Ferraiolo <jon.ferraiolo@adobe.com>, Cameron McCormack <cam-www-svg@aka.mcc.id.au>, www-svg@w3.org

Peter Sorotokin wrote:

>>>> 2)  That the implementation is keeping the event listeners for the 
>>>> two types in
>>>>     separate lists (is this desirable?  Should registering a 
>>>> listener for both
>>>>     types involved make it get the event twice?).
>>>
>>> You can do it per-listener rather than on per-list basis; but I'd 
>>> keep two separate lists.
>>
>>
>> In other words, a listener registered for both event names would 
>> indeed get the event twice?
> 
> No, in this case each event listener entry in the list would have to 
> store an event type for which it was registered (also would be needed 
> for unregistering).

I'm sorry, but I think you lost me.  Say I have an event listener named 
"listener" and an event target named "target".  We have our two event types 
"type1" and "type2".  I execute the following code:

   target.addEventListener("type1", listener, false);
   target.addEventListener("type2", listener, false);

when the event fires, how many times will my listener's handleEvent method be 
called?  Please note the provisions on addEventListener for registering 
identical listeners.

Further, what is the behavior of:

   target.addEventListener("type1", listener, false);
   target.removeEventListener("type2", listener, false);

?

The answers to these questions should be clearly documented in the specification 
of what it means for the two event names to be "equivalent".

-Boris
Received on Wednesday, 19 January 2005 00:59:05 GMT

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