attachBrowserEvent is triggered twice

[martinr92]

Hello UI5-Developers,

I've got the problem, that every keydown event is triggered twice.
Please take a look at the short example.
JSBin

Always when you press one key, the counter cntr variable is increased 2 times.
Do you have any idea, how to fix this?

Thanks for your help.
Greetings
Martin

[akudev]

Hi Martin,
you should not register this kind of handler in onAfterRendering because it can and will be called multiple times and you never deregister, so you get more and more listeners.
When you register in the onInit function of the controller, it works as expected:
http://jsbin.com/vokofukalu/1/edit

However, the straightforward deduction that onAfterRendering is called twice here does not apply. It is only called once (otherwise it would in fact be a performance bug). However, this means that I don't have an explanation yet why your listener is called twice when attached in onAfterRendering...

This needs further analysis.

Andreas

[martinr92]

Hi Andreas,
Thanks for your fast response and the great solution.
Moving the handler registration in the onInit function works pretty well.

[akudev]

Hi Martin,
glad that we were able to help you!
But I'd still like to see this behavior understood. -> reopening

Andreas

[akudev]

Ok, the issue is that the browser event handlers are detached before rerendering and re-attached after rendering. However, when you register in onAfterRendering, the handler is 1.) immediately attached and 2.) re-attached by the RenderManager, so this is where the duplicate registration comes from.

This is indeed a bug. Thanks for spotting this!
Internal reference: 1472004194.

[simlin]

The issue should be solved in master and 1.26.4 via the following commits:
c317049
f879f16

[cheungkonghou]

it's happening again in v.1.40.8... I simply put a console.log inside onAfterRendering and it's called twice.

[codeworrior]

Is onAfterRendering called twice (which can happen depending on the scenario) or is the event handler indeed attached twice?

[cheungkonghou]

simply something like this:
onAfterRendering: function(){ console.log('controller onAfterRendering'); ... },

[codeworrior]

Well, that's most likely normal behaviour. See #1162 (comment) for a description of the rendering process. As explained there, any control (or view) might be rendered multiple times if there are updates to its configuration.

If you think there is indeed a problem, we need a more detailed description of the scenario, ideally as a JSBin. And if so, I would propose to open a new issue as yours seems not to be immediately related to the duplicate attachBrowserEvent that was discussed here.

[cheungkonghou]

My case is: I use an XML view with some native html elements in it (using xhml namespace), and then I'll use some 3rd party plugins on those elements. However those elements got inited again when the view is re-rendered. Is there any solution to achieve this?

[cheungkonghou]

Moreover I am confused that when I use a IconTabBar to switch between tabs, the tab content got re-rendered again but no onBeforeRendering or onAfterRendering event is sent...