Hi Sebastien,
On Wed, Jul 31, 2013 at 2:37 PM, Sebastien <seb...@gmail.com> wrote:
> Hi,
>
> I agree with Igor. Just have to take care that binding to document is not a
> default behavior for all bound events, and that it should be use with care.
>
I think Igor said the opposite - bind on document with child selector:
$(document).on('click', '[data-w-click]', handler);
> (IMHO, the javadoc should be enough)
> Martin, I unfortunately did not had the chance to have a look at your code
> now... :s But, if it not the case, if think EventDelegatingBehavior should
> have a constructor that take a component (the datatable for instance) as an
>
Behavior#bind(Component) gives you a reference to the component. No need to
pass it as ctor parameter.
> argument so the event can be bound it it instead of the document (by
> getting its markupid as the selector)...
> [quote]
> Here is another important tips "*Attaching many delegated event handlers
> near the top of the document tree can degrade performance*". For best
> performance, attach delegated events at a document location as close as
> possible to the target elements as done in above jQuery code
> [/quote]
>
>
> http://jquerybyexample.blogspot.com/2013/04/direct-vs-delegated-events-with-jquery-on-method.html
According to this article it is better to bind on the table than on the
document.
At least this is how I read it.
>
>
>
> I think events delegation would be a great addition anyhow...
>
> Best regards,
> Sebastien.
>
>
>From the discussion so far I see these two issues which need to be solved
before starting make changes in the code:
1) it must be possible to use event delegation on "the table", not only on
the document
2) if the ajax attributes are stored in data-w-eventName attribute on the
element then we need to figure out where to store the Ajax call listeners'
functions
For 1) I see it as a new Ajax request attribute - bindOnComponent = true
If the attribute is 'false' then the event will be bound on the document
instead and will use event delegation.
This way all <td>s can return false, and the <table> can return true to
handle the bubbling event (and stop it, because otherwise it will be
handled twice when the event reaches the document)
For 2) We can introduce global registry (e.g.
Wicket.Ajax.Handlers[markupId][handlerType] =>
Wicket.Ajax.Handlers["someId12"]["success"] = function(...) {...}).
So the "global" handler (bound on the table or on the document) can use the
specific Ajax call listeners for the clicked element with attribute
'data-w-eventName'
WDYT ?
>
>
> On Tue, Jul 30, 2013 at 7:07 PM, Igor Vaynberg <igor.vaynb...@gmail.com
> >wrote:
>
> > binding on document is fine, you just have to make sure your code is fast
> > in case you are binding to things like mousemove.
> >
> > -igor
> >
> >
> > On Tue, Jul 30, 2013 at 1:31 AM, Martin Grigorov <mgrigo...@apache.org
> > >wrote:
> >
> > > On Fri, Jul 12, 2013 at 5:21 PM, Igor Vaynberg <
> igor.vaynb...@gmail.com
> > > >wrote:
> > >
> > > > On Fri, Jul 12, 2013 at 1:50 AM, Martin Grigorov <
> mgrigo...@apache.org
> > >
> > > > wrote:
> > > > > On Fri, Jul 12, 2013 at 8:59 AM, Igor Vaynberg <
> > > igor.vaynb...@gmail.com
> > > > >wrote:
> > > > >
> > > > >> On Thu, Jul 11, 2013 at 7:22 AM, Martin Grigorov <
> > > mgrigo...@apache.org>
> > > > >> wrote:
> > > > >> > On Thu, Jul 11, 2013 at 4:48 PM, Sven Meier <s...@meiers.net>
> > > wrote:
> > > > >> >
> > > > >> >> Hi,
> > > > >> >>
> > > > >> >>
> > > > >> >> >The idea with plain JS solution I cannot visualize in my head
> > yet.
> > > > >> >>
> > > > >> >> EventDelegatingBehavior is just a collector of JavaScript
> > snippets.
> > > > The
> > > > >> >> actual magic runs in the browser: a custom bubbling of events
> and
> > > > >> >> delegation to the actual behavior.
> > > > >> >> It should be possible to do this plain with JavaScript:
> > > > >> >>
> > > > >> >> public class DelegatingAjax implements IAjax {
> > > > >> >>
> > > > >> >> public ajax(IHeaderResponse response, Component component,
> > > > >> >> AjaxRequestAttributes attributes) {
> > > > >> >> CharSequence ajaxAttributes =
> > > renderAjaxAttributes(**component,
> > > > >> >> attributes);
> > > > >> >>
> > > > >> >>
> > > > >>
> > > >
> > >
> >
> response.render(**OnDomReadyHeaderItem.**forScript("Wicket.Event.***delegate*("
> > > > >> >> + ajaxAttributes + ");");
> > > > >> >> }
> > > > >> >> }
> > > > >> >>
> > > > >> >> This would be page-global though.
> > > > >> >
> > > > >> >
> > > > >> > This is an important detail!
> > > > >> > I'll consult with my frontend colleagues but so far I don't see
> > > > problems.
> > > > >> >
> > > > >> > For every delegated component we can set special CSS class, e.g.
> > > > >> > 'wicket-delegated'.
> > > > >> > The binding will be: $(document).on('click',
> '.wicket-delegated',
> > > > >> > function(event) {....})
> > > > >> > i.e. we will take advantage of jQuery delegation/live support.
> > > > >> > This way even newly added items in the repeaters will be
> > > automatically
> > > > >> > supported.
> > > > >>
> > > > >>
> > > > >> this is partially on the right track, but there are still some
> > > > >> optimization that can be made.
> > > > >>
> > > > >> first, the ajax attributes need to be moved into a data attribute
> > that
> > > > >> is written out on the tag. the final output of attaching a onclick
> > > > >> ajax behavior to a tag should end up looking like this:
> > > > >>
> > > > >> <a wicket:id="ajaxlink"
> > > > >> data-w-click="u/?0.foo:bar.ILinkListener/c/default/pd/true"/>
> > > > >>
> > > > >> (we will need to figure out how to encode ajax attributes into a
> > > string)
> > > > >>
> > > > >
> > > > > example:
> > > > > <a id="c23" data-w-attrs='{"u":"someUrl","m":"post"}' ...>
> > > > >
> > > > > $('#c23').data("w-attrs") === {u: "someUrl", m: "post"}
> > > > >
> > > > > This works for valid JSON, but it doesn't for the enhancement we
> use
> > -
> > > > the
> > > > > functions for the call listeners.
> > > >
> > > > i did say we need to figure out a way to encode it right above the
> > > example
> > > > :)
> > > >
> > > > >> then you can have the one global listener:
> > > > >>
> > > > >> $(document).on("click", function(e) {
> > > > >>
> > > > >
> > > > > The problem here is that using 'document' will make the things
> > actually
> > > > > slower.
> > > > > We need to find a simple way to be able to bind on a parent
> > component.
> > > > > In Sven's example - a table with many cells the most appropriate
> > > element
> > > > is
> > > > > the <table> itself.
> > > >
> > > > umm, why does it make things slower exactly? this has virtually no
> > > > overhead, events bubble up anyways...so where does the slowness come
> > > > from?
> > > >
> > >
> > > All the talks about the deprecation of jQuery#live() say that binding
> on
> > > the document is not a good idea (performance wise).
> > >
> > > If it is not possible to bind on a context element then I see no much
> > > benefit.
> > >
> > >
> > > >
> > > > -igor
> > > >
> > > > >
> > > > > In event-delegating-behavior branch I need to traverse the parent
> > > > > components and their behaviors to be able to find the appropriate
> > > parent.
> > > > > So we win some performance in JS execution but lose some in Java
> :-/
> > > > >
> > > > > var element=$(this), attrs=element.attr("data-w-click");
> > > > >> if (attrs&&!e.handledByWicket)
> > > > >> Wicket.Ajax.call(attrs);
> > > > >> e.handledByWicket=true; // if there are more handlers
> above,
> > do
> > > > >> not double process the event - read below
> > > > >> }
> > > > >> }
> > > > >>
> > > > >> the advantage here is that we only have one javascript listener
> that
> > > > >> needs to be registered.
> > > > >>
> > > > >> however, there are a few disadvantages:
> > > > >> * event propagation options wont work anymore, because the event
> has
> > > > >> to propagate all the way to the document in order to trigger.
> > > > >> * some libraries block events. for example if there is a panel
> with
> > an
> > > > >> ajax link inside a third party modal window. the modal window lib
> > may
> > > > >> prevent any clicks from propagating out of itself, which means the
> > > > >> handler on the document will never see them.
> > > > >>
> > > > >> we can sort of solve this by having a behavior that would write
> out
> > > > >> the listener above, but attached to the component not the
> document.
> > > > >>
> > > > >> that way, if we look at my example with the panel inside the
> modal,
> > > > >> the user can add this behavior to the panel that will be in the
> > modal
> > > > >> and still be able to capture the event.
> > > > >>
> > > > >> this does, however, make troubleshooting more difficult. why didnt
> > my
> > > > >> ajax event trigger? you will have to be a lot more aware about
> what
> > > > >> javascript you have in the dom.
> > > > >
> > > > >
> > > > >> i think a short term goal might be to move the ajax attributes
> into
> > a
> > > > >> dom attribute and change our ajax code to simply say
> > > > >> Wicket.Ajax.bind("click", "component234");
> > > > >>
> > > > >
> > > > > see above (valid JSON)
> > > > >
> > > > > we can enrich the DOM:
> > > > > <a ... onsuccess="someScript">
> > > > > but I think this is a step back to Wicket 1.5 days (ajax decorators
> > on
> > > > > strings, etc.)
> > > > >
> > > > >
> > > > >>
> > > > >> this will register the listener like above on the element
> directly.
> > so
> > > > >> no delegation yet but cleaner javascript/html. also the browser
> > doesnt
> > > > >> have to parse as much javascript, so it will be a bit speedier.
> > > > >>
> > > > >> potentially we can collect ids to further optimize js size:
> > > > >> Wicket.Ajax.bind({click, ["c34", "c32"], blur: ["c22","c98"]);
> > > > >>
> > > > >> -igor
> > > > >>
> > > > >>
> > > > >> >
> > > > >> >
> > > > >> >>
> > > > >> >>
> > > > >> >> Sven
> > > > >> >>
> > > > >> >>
> > > > >> >>
> > > > >> >> On 07/11/2013 03:40 PM, Martin Grigorov wrote:
> > > > >> >>
> > > > >> >>> On Thu, Jul 11, 2013 at 4:30 PM, Nick Pratt <
> nbpr...@gmail.com>
> > > > wrote:
> > > > >> >>>
> > > > >> >>> I think this is great - we have some tables now with a ton of
> > JS
> > > > >> events
> > > > >> >>>> on
> > > > >> >>>> the child elements. Just to clarify, will this make the
> > rendered
> > > > page
> > > > >> >>>> smaller since there will only be a single JS handler for the
> > > event
> > > > for
> > > > >> >>>> the
> > > > >> >>>> container rather than N JS handlers?
> > > > >> >>>>
> > > > >> >>>> At the moment all attributes for an inner element are
> > preserved.
> > > > >> >>> 'e' (the event name), 'c' (the component markup id), pd
> (prevent
> > > > >> default),
> > > > >> >>> sp (stop propagation) can be removed because they are not
> really
> > > > used.
> > > > >> >>> But every inner element can have its own call listeners, form
> > > > >> submitters
> > > > >> >>> can also have custom settings ('f', 'sc', 'mp', 'm'), so I
> think
> > > > they
> > > > >> have
> > > > >> >>> to be preserved.
> > > > >> >>> If you look in #updateAjaxAttributes() for your ajax behaviors
> > in
> > > > your
> > > > >> >>> table cells you will probably notice that they have their own
> > > > >> attributes.
> > > > >> >>>
> > > > >> >>>
> > > > >> >>> Making it switchable (I think how Sven suggested) would be an
> > > > >> >>>> improvement -
> > > > >> >>>> we could leave it off by default, but provide a simple switch
> > on
> > > a
> > > > >> >>>> per-container (or per-app) basis that would allow the dev to
> > > > choose.
> > > > >> >>>>
> > > > >> >>>> Yes, it looks as an improvement.
> > > > >> >>> Moving the current code to such implementation is easy.
> > > > >> >>> The idea with plain JS solution I cannot visualize in my head
> > yet.
> > > > >> >>>
> > > > >> >>>
> > > > >> >>> Regards
> > > > >> >>>>
> > > > >> >>>> Nick
> > > > >> >>>>
> > > > >> >>>> On Thu, Jul 11, 2013 at 4:59 AM, Martin Grigorov <
> > > > >> mgrigo...@apache.org
> > > > >> >>>>
> > > > >> >>>>> wrote:
> > > > >> >>>>> Hi,
> > > > >> >>>>>
> > > > >> >>>>> At https://github.com/apache/**wicket/compare/event-**
> > > > >> >>>>> delegating-behavioryou<
> > > > >>
> > https://github.com/apache/wicket/compare/event-delegating-behavioryou
> > > >
> > > > >> >>>>> may see the diff between master and
> event-delegating-behavior
> > > > >> branches.
> > > > >> >>>>>
> > > > >> >>>>> The latter provides a new AjaxEventBehavior (AEB) -
> > > > >> >>>>>
> > > > >> >>>> EventDelegatingBehavior
> > > > >> >>>>
> > > > >> >>>>> (EDB), that suppresses the JS event binding for all
> > > > >> AjaxEventBehaviors
> > > > >> >>>>>
> > > > >> >>>> for
> > > > >> >>>>
> > > > >> >>>>> a given event type (click, submit, change, ...) in the
> > children
> > > > >> >>>>>
> > > > >> >>>> components
> > > > >> >>>>
> > > > >> >>>>> of the host component of EDB.
> > > > >> >>>>>
> > > > >> >>>>> How EDB works:
> > > > >> >>>>>
> > > > >> >>>>> - until now AjaxEventBehavior#renderHead() renders
> ondomready
> > > > header
> > > > >> >>>>> item
> > > > >> >>>>> with JS snippet like:
> > > > >> >>>>> Wicket.Ajax.ajax(**attributesObject);
> > > > >> >>>>> In the new branch there is a check if some parent has EDB
> for
> > > the
> > > > >> event
> > > > >> >>>>> type of this AEB, and if there is such then the AEB
> "donates"
> > > its
> > > > >> >>>>> attributes to the EDB.
> > > > >> >>>>>
> > > > >> >>>>> - EventDelegatingBehavior#**getCallbackScript() renders :
> > > > >> >>>>> Wicket.Event.delegate('**edbComponentMarkupId', 'eventType',
> > > > >> >>>>> edbAttributes,
> > > > >> >>>>> childrenAttrsMap);
> > > > >> >>>>>
> > > > >> >>>>> - when a delegated component fires its event (e.g. the user
> > > clicks
> > > > >> on an
> > > > >> >>>>> AjaxLink) the event is handled by EDB's event handler. It
> > > extracts
> > > > >> the
> > > > >> >>>>> markupId of the inner HTML element and fires
> Wicket.Ajax.Call
> > > with
> > > > >> the
> > > > >> >>>>> specific attributes for the extracted inner element.
> > > > >> >>>>>
> > > > >> >>>>> Pros:
> > > > >> >>>>>
> > > > >> >>>>> - simple to use - just add EDB to a container component
> around
> > > > your
> > > > >> Ajax
> > > > >> >>>>> heavy component (e.g. repeater with many Ajax behaviors).
> See
> > > the
> > > > >> demo
> > > > >> >>>>>
> > > > >> >>>> app
> > > > >> >>>>
> > > > >> >>>>> at https://issues.apache.org/**jira/browse/WICKET-5267<
> > > > >> https://issues.apache.org/jira/browse/WICKET-5267>
> > > > >> >>>>>
> > > > >> >>>>> - faster JS execution
> > > > >> >>>>> -- faster execution of the domready handler because there is
> > > just
> > > > one
> > > > >> >>>>> binding instead of N
> > > > >> >>>>> -- faster reaction because the browser finds the event
> handler
> > > > much
> > > > >> >>>>>
> > > > >> >>>> faster.
> > > > >> >>>>
> > > > >> >>>>> I wasn't able to prove this with numbers because there is no
> > way
> > > > to
> > > > >> >>>>>
> > > > >> >>>> detect
> > > > >> >>>>
> > > > >> >>>>> the 'start time', i.e. when the user makes the action. With
> JS
> > > the
> > > > >> >>>>>
> > > > >> >>>> earliest
> > > > >> >>>>
> > > > >> >>>>> point is when the browser has already looked up the event
> > > handler.
> > > > >> >>>>> Chrome Dev tools (timeline, profiling, pagespeed) don't help
> > > too.
> > > > So
> > > > >> my
> > > > >> >>>>> reference that it is faster are the articles in the web and
> a
> > > use
> > > > >> case
> > > > >> >>>>> in
> > > > >> >>>>> our application.
> > > > >> >>>>>
> > > > >> >>>>> Cons:
> > > > >> >>>>>
> > > > >> >>>>> - AEB#renderHead() needs to check whether there is EDB up in
> > the
> > > > >> >>>>>
> > > > >> >>>> hierarchy
> > > > >> >>>>
> > > > >> >>>>> to be able to decide what to do.
> > > > >> >>>>> This is ugly, I agree. But I see no other solution that will
> > > > preserve
> > > > >> >>>>> the
> > > > >> >>>>> transparent usage of something like EDB and will not
> require a
> > > > major
> > > > >> >>>>> rewrite of user applications to be able to use event
> > delegation.
> > > > >> >>>>> -- there are some optimizations to lower the impact of the
> new
> > > > >> checks:
> > > > >> >>>>> --- a new setting (IAjaxSettings#**useEventDelegation) - a
> > > global
> > > > >> >>>>> property
> > > > >> >>>>> that prevents visiting the parent components and their
> > behaviors
> > > > for
> > > > >> all
> > > > >> >>>>> apps which do not use EDB
> > > > >> >>>>> --- when EDB is bound it registers a metadata for its event
> > type
> > > > in
> > > > >> the
> > > > >> >>>>> page instance. This prevents visiting all behaviors of all
> > > parent
> > > > >> >>>>> components
> > > > >> >>>>>
> > > > >> >>>>>
> > > > >> >>>>> I have no more ideas how to further optimize it.
> > > > >> >>>>>
> > > > >> >>>>> Any feedback is welcome! Even if you have a completely
> > different
> > > > idea
> > > > >> >>>>> how
> > > > >> >>>>> to implement this functionality.
> > > > >> >>>>>
> > > > >> >>>>> Thanks for reading!
> > > > >> >>>>>
> > > > >> >>>>>
> > > > >> >>
> > > > >>
> > > >
> > >
> >
>
