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Event class for jQuery
in Developing jQuery Core
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3 years ago
Feedback please! :)
I really like (and support) this feature.
http://dev.jquery.com/ticket/3662
Also... I know that the returned value from jQuery.fn.trigger is used
here and there (jQuery UI?). But that behavior is really odd and
fragile in my opinion (false overrides any previous value).
I think it'd be nice to return true/false depending on whether
e.preventDefault() was called. This would be very useful for custom
events, to allow event handlers to stop a scheduled (custom) behavior.
As an alternative, we could add e.isDefaultPrevented() that retrieves
this value from the event object.
Note that none of this last 2 behaviors (or the one in the ticket) is
my invention.
I'm just imitating AS3's event system. I suppose that belongs to some
EcmaScript specification as well.
http://docs.brajeshwar.com/as3/flash/events/Event.html
Thanks
--
Ariel Flesler
http://flesler.blogspot.com
Replies(18)
Re: Event class for jQuery
3 years ago
Ariel,
+ 1 for me...Good you found that something needs to be reworked again
there.
A quite similar approach was firstly tested in the "event.fix()"
optimizations in 1.2.3.
At that time my proposal was an "event.create()" function returning an
object but I like your approach, it is probably better, especially if
it offers a consistent solution for both "event.fix()" and
"event.trigger".
The created events (especially for custom and object events) don't
need to have copied all those properties, the type, the 3 targets,
eventPhase, preventDefault() and stopPropagation() and very few extra
properties are the one needed in 99% of the cases, by saving in it a
copy of the "originalEvent" all those properties will be available
anyway (maybe through a getter if that is preferred).
Two suggestions I have for "event.js":
- add the capture flag, W3C specs, so delegation may be wired directly
through existing code
- make a distinction between firing events on DOM elements and
triggering events on objects
Manual firing of events on DOM elements seems to be handled in a more
standard way by native "dispatchEvent()" or "fireEvent()" and you get
the benefit of letting co-existing code know this happened.
jQuery.event meeting Prototype Event ?
--
Diego
Leave a comment on diego.perini's reply
Re: Event class for jQuery
3 years ago
jQuery UI uses the return value of triggerHandler, but we only care
about false, so this change shouldn't affect us.
What's the logic behind removing the event from the extra function?
If I remember correctly, I talked to John about this a while ago and
he couldn't think of any reason why that was done. I created a ticket
to remove this behavior and it has just been sitting in Trac for 5
months ( http://dev.jquery.com/ticket/3096 ).
Leave a comment on scott.gonzalez's reply
Re: Event class for jQuery
3 years ago
@Scott
Ok, that's an easy change (leave it or remove it). The question is,
what's the formal application of this extra function ?
@Diego
We don't have the needed hacks to implement event capturing in IE (I
know your NWEvents does). We don't plan to add that I think, that
requires a lot of hacking and not many would benefit from it.
So why add that parameter to our method ?
I've been thinking about trying native event triggering instead of
what we have now. I showed that old experiment where I achieved native
event bubbling on all browsers, even for custom events. But that
required quite a large amount of code, maybe we can leave that as a
plugin.
About the event properties from the originalEvent... jQuery "claims"
it normalizes event objects in a cross browser way (some properties).
Telling the user "look for them on the original object" doesn't seem
too nice for me.
Thanks both for replying.
Cheers
Leave a comment on flesler's reply
Re: Event class for jQuery
3 years ago
Addition:
http://dev.jquery.com/ticket/3665
Feedback please.
--
Ariel Flesler
http://flesler.blogspot.com
Leave a comment on flesler's reply
Re: Event class for jQuery
3 years ago
I like this as well but I definitely wouldn't take away the ability to just pass in the event type as a string to trigger. I don't want to have to create an event object every time I want to trigger an event but wouldn't mind passing it in if I already had it on hand. This will provide a nice way to extend the event object itself. I believe Nathan Hammond was asking about this in a thread recently on this list.<div>
</div><div>--</div><div>Brandon Aaron
</div><div>--</div><div>Brandon Aaron
Leave a comment on brandon_aaron's reply
Re: Event class for jQuery
3 years ago
Ariel,
jQuery is already doing very well in many fields, the suggestions were
to cover expressed needs not to leave out working code.
I will follow on your answers...
Leave a comment on diego.perini's reply
Re: Event class for jQuery
3 years ago
<html><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; ">+1 for not taking away the ability to pass in the event type as a string to trigger. I think it would break a lot of pre-existing code if that were to happen.
<div apple-content-edited="true"> <span class="Apple-style-span" style="border-collapse: separate; color: rgb(0, 0, 0); font-family: Helvetica; font-size: 13px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-align: auto; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0; "><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><span class="Apple-style-span" style="border-collapse: separate; color: rgb(0, 0, 0); font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; "><span class="Apple-style-span" style="border-collapse: separate; color: rgb(0, 0, 0); font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; "><div><br class="Apple-interchange-newline">--Karl</div><div><br class="Apple-interchange-newline">____________</div><div>Karl Swedberg</div><div><a href="http://www.englishrules.com">www.englishrules.com</a></div><div><a href="http://www.learningjquery.com">www.learningjquery.com</a></div><div>
</div></span><br class="Apple-interchange-newline"></span><br class="Apple-interchange-newline"></div></span> </div>
<div><div>On Nov 29, 2008, at 11:48 AM, Brandon Aaron wrote:</div><br class="Apple-interchange-newline"><blockquote type="cite">I like this as well but I definitely wouldn't take away the ability to just pass in the event type as a string to trigger. I don't want to have to create an event object every time I want to trigger an event but wouldn't mind passing it in if I already had it on hand. This will provide a nice way to extend the event object itself. I believe Nathan Hammond was asking about this in a thread recently on this list.<div>
</div><div>--</div><div>Brandon Aaron
<div apple-content-edited="true"> <span class="Apple-style-span" style="border-collapse: separate; color: rgb(0, 0, 0); font-family: Helvetica; font-size: 13px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-align: auto; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0; "><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><span class="Apple-style-span" style="border-collapse: separate; color: rgb(0, 0, 0); font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; "><span class="Apple-style-span" style="border-collapse: separate; color: rgb(0, 0, 0); font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; "><div><br class="Apple-interchange-newline">--Karl</div><div><br class="Apple-interchange-newline">____________</div><div>Karl Swedberg</div><div><a href="http://www.englishrules.com">www.englishrules.com</a></div><div><a href="http://www.learningjquery.com">www.learningjquery.com</a></div><div>
</div></span><br class="Apple-interchange-newline"></span><br class="Apple-interchange-newline"></div></span> </div>
<div><div>On Nov 29, 2008, at 11:48 AM, Brandon Aaron wrote:</div><br class="Apple-interchange-newline"><blockquote type="cite">I like this as well but I definitely wouldn't take away the ability to just pass in the event type as a string to trigger. I don't want to have to create an event object every time I want to trigger an event but wouldn't mind passing it in if I already had it on hand. This will provide a nice way to extend the event object itself. I believe Nathan Hammond was asking about this in a thread recently on this list.<div>
</div><div>--</div><div>Brandon Aaron
Leave a comment on kswedberg's reply
Re: Event class for jQuery
3 years ago
@Brandon & Karl
Uh ? no one said we'd remove that... check the patch before jumping to
conclusions :D
Leave a comment on flesler's reply
Re: Event class for jQuery
3 years ago
I did, just wanted to make it very clear. :)<div>
</div><div>--</div><div>Brandon Aaron
</div><div>--</div><div>Brandon Aaron
Leave a comment on brandon_aaron's reply
Re: Event class for jQuery
3 years ago
Anyone else that "concretely" agrees or disagrees with any of the 2
mentioned tickets ?
Thanks
--
Ariel Flesler
http://flesler.blogspot.com
Leave a comment on flesler's reply
Re: Event class for jQuery
3 years ago
This looks good - just one point that I wanted to mention: We really
need a way to still get at the return values of the triggered
callbacks. I agree with your decision to move to using the W3C-style
of return values. Perhaps we could use a property like .returnValue to
maintain the last return value from the functions. Or even something
like .returnValues.
The reason why I bring this up is that it's becoming increasingly
common for developers to use jQuery events as a way of doing custom
events for communication and moving in this direction simply provides
an extra level of indirection for them to dance through.
Even with my proposal in order to get the previously-available return
value a developer would have to do:
var evt = new jQuery.Event("something");
$(foo).trigger(evt);
evt.returnValue
Which is very clumsy. I might be ok with a new method - something akin
to .triggerHandler but with the addition of returning the returnValue.
Another point I want to mention: We're exposing jQuery.Event for
developers to use but this is the first time that we've explicitly
asked them to instantiate anything (new jQuery.Event). I'd like to
request that the 'new' not be used - much in the same way that
developers don't have to do 'new jQuery' (since we hide that away).
--John
need a way to still get at the return values of the triggered
callbacks. I agree with your decision to move to using the W3C-style
of return values. Perhaps we could use a property like .returnValue to
maintain the last return value from the functions. Or even something
like .returnValues.
The reason why I bring this up is that it's becoming increasingly
common for developers to use jQuery events as a way of doing custom
events for communication and moving in this direction simply provides
an extra level of indirection for them to dance through.
Even with my proposal in order to get the previously-available return
value a developer would have to do:
var evt = new jQuery.Event("something");
$(foo).trigger(evt);
evt.returnValue
Which is very clumsy. I might be ok with a new method - something akin
to .triggerHandler but with the addition of returning the returnValue.
Another point I want to mention: We're exposing jQuery.Event for
developers to use but this is the first time that we've explicitly
asked them to instantiate anything (new jQuery.Event). I'd like to
request that the 'new' not be used - much in the same way that
developers don't have to do 'new jQuery' (since we hide that away).
--John
Leave a comment on jeresig's reply
Leave a comment on scott.gonzalez's reply
Re: Event class for jQuery
3 years ago
I think the only common use for the returned data from event handlers
is the (get|set)Data events, which in my opinion, are already weird.
I think we should re-think some of these things.
As for hiding the new from $.Event... hm... I really disagree. I don't
see why we should conceal OO.
I understand that (because of chaining) $('foo') is nicer than new $('foo').
But not for the event object. It is an object and I see no need to
hide this. Just my opinion.
Leave a comment on flesler's reply
Re: Event class for jQuery
3 years ago
How about allowing passing of a plain object that is then copied into
an Event object:
$(...).trigger({type: 'change', customfield: 'something', target:
myelement});
$.fn.trigger = function(arg) {
if (typeof arg === 'object') {
ev = $.extend(new $.Event(), arg);
}
...
}
And also detect whether the arg is actually an $.Event object first,
and just use it as it comes.
Leave a comment on jollytoad's reply
Re: Event class for jQuery
3 years ago
Could do, I'll check this a little more in depth, later.
Thanks
Leave a comment on flesler's reply
Re: Event class for jQuery
3 years ago
Ok, took me more than an hour but I finally updated the patch to fit
all the new changes in the trunk (live,event bubbling,etc).
I added a 'currentTarget' attribute to the event object which reflects
the actual element while bubbling, while 'target' keeps the original.
I added the possibility to pass a literal object as THE event object
({type:'click',foo:'bar'}). It gets copied to a real one afterwards.
I think this is enough to satisfy John's request. One isn't FORCED to
use the 'new' keyword. But it is possible.
While it is nice to use jQuery without 'new'. One cannot extend it if
desired.
jQuery.Event can be surely extended, so I think hiding its OO source
would just confuse someone trying to extend it.
We could have a plugin that adds MouseEvent and KeyboardEvent, as an
easy way to simulate those.
In addition, event objects have a 'stopImmediatePropagation' method to
kill the following handlers. This was added some time ago.
http://dev.jquery.com/changeset/6005
Cheers
--
Ariel Flesler
http://flesler.blogspot.com
Leave a comment on flesler's reply
Re: Event class for jQuery
3 years ago
jQuery.Event can be now instantiated without the 'new' operator, still
optional.
http://dev.jquery.com/changeset/6008
--
Ariel Flesler
http://flesler.blogspot.com
Leave a comment on flesler's reply
Re: Event class for jQuery
3 years ago
Major commit for jQuery.Event/jQuery.event.trigger with features,
enhancements and bug fixes.
http://dev.jquery.com/changeset/6016
--
Ariel Flesler
http://flesler.blogspot.com
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