Angular's @hostListener is well known within the community. Rather unknown are the problems this might have on runtime performance and general appl...
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It is probably better to use Renderer2 for listening instead of directly accessing the native element.
I think so. Renderer2 have
listenmethod to do that.Oh thanks a lot for this feedback. I didn't know that before. I'll update the blog post today
Renderer2 listen method doesn't have params that have addEventListener. Actually it's the same as @HostListener.
Regarding the "The problem here is that we register the 3 event listener, mentioned above, for every component instance, even though it's impossible to drag'n'drop multiple rectangles at the same time." Actually this approach allow us to dag'n'drop multiple elements at once. Managed to do that 4 times on 2 different computers when testing how the code decides which rectangle to pick up when they overlap.
Good example that shows that Angular does not fully embrace RxJs Technology (It even hides it with EventEmitter, Input -> SimpleChanges). Now Angular team even takes into considerations to replace RxJs with Promises (ngconf 2022).
Angular's big merit on Web Platform is that it made Typescript and RxJs known to the Web Community. These two Technologies are so fundamental that they will outlive Angular.
Nice post! I recently started using fromEvent, cool stuff can be done with it also!
I started using it, for debounced input search, to not perform more requests than needed.
For observing inputs, you might consider using reactive forms and subscribing to the valueChanges observable on the form or formControl in question.
Ohh true, I did not consider this approach, I didn't like to have to pass in the element reference to
fromEvent, I don't usually like manipulating elements directly so the reactive form could be a really nice solution.Thanks for the info!
That won't help with
enterkey which is often used.Thanks for article!
Btw takeUntil(mouseDown$) will complete the sequence. Should we add repeat() to ressurect it ?
the takeUntil is applied to the inner stream and we don't want this to repeat. It is going to be recreated with the next notification coming from the fromEvent. The indention is propably a little bit missleading
Ah, yes! Missed that it is for inner observable, thanks
You can solve all of these problems using Angular's Event Plugins and still use HostListener. It is the cleaner and clearer way of writing listeners in Angular.
Your RxJS code is broken, btw.