[whatwg] Detecting eventListeners

[Rick Waldron]

On Thursday, May 24, 2012 at 10:45 PM, Xavier Ho wrote:  
> Hello Jason,
>  
> On 25 May 2012 12:33, Jason Edward 今井 Parrott <parrott.jason at gmail.com>wrote:
>  
> > Personally, I wouldn't want some random library listening and
> > possibly forcibly removing my event listeners.
> > Some bad script could do this easily.
> >  
>  
>  
> That's not what I'm asking. I'm asking to check if an event listener
> exists, not to remove it.
>  
But once the door is open, there is no way to close it.
  
>  
>  
> > However, you could use some prototyping tricks to make this work (hint:
> > overload Node.prototype.addEventListener)
> >  
>  
>  
> We could add 1000 lines of code that overrides every single
> addEventListener on any arbitrary HTMLNode. That's a great solution.
>  
>  


Please save the dramatics, it would hardly take 1000 lines of code to accomplish this.

I suspect there is likely a simpler alternative solution to your problem - that doesn't involve new spec features.

Rick
>  
> Tongue-in-cheekly yours,
> Xav
>  
>  
>  
>  
> >  
> >  
> > On Fri, May 25, 2012 at 10:34 AM, Xavier Ho <contact at xavierho.com> wrote:
> >  
> > > Hello,
> > >  
> > > We're working on a project that requires detection of registered event
> > > listeners. Our targets are old-style "onclick" attribute bindings, events
> > > registered via "addEventListener" (and the IE equivalent), and other
> > > custom
> > > event libraries such as jQuery's.
> > >  
> > > As far as we can tell, there is no way to determine if an element has an
> > > eventListener attached to it, created via "addEventListener". There is a
> > > sure way to remove an event (via "removeEventListener"), but we want to
> > > enter some code path if and only if an element has an event registered,
> > > without altering its eventListener. This is currently not possible.
> > >  
> > > Many discussions about this topic has been raised in the past. This
> > > Stackoverflow answer has a good summary:
> > >  
> > > http://stackoverflow.com/questions/7810534/have-any-browsers-implemented-the-dom3-eventlistenerlist
> > >  
> > > As far as the author could tell, this feature was never implemented due to
> > > a lack of a use-case. We have a use-case. Could someone share some
> > > thoughts on this?
> > >  
> > > We are also happy to hear workarounds, if anyone has previously
> > > encountered
> > > this issue and found a way.
> > >  
> > > Cheers,
> > > Xav
> > >  
> >  
> >  
>  
>  
>