ResizeObserver callback is not running in zone

[bene-starzengruber]

Which @angular/* package(s) are the source of the bug?

core, zone

Is this a regression?

I dont think so, same behaviour as in Angular 12

Description

The callback of a ResizeObserver is not running in the ngZone and does therefore not trigger change detection, even if .markForCheck() is called manually

Please provide a link to a minimal reproduction of the bug

angular 13: https://stackblitz.com/edit/angular-ivy-cuegz9?file=src/app/app.component.ts
(have a look at the comments in ngOnInit and resize the preview tile on the right to see the effect)

angular 12: https://stackblitz.com/edit/base-angular-12-app-uh71an?file=src/app/app.component.ts

Anything else?

there are issues regarding the ResizeObserver and fakeAsync but I'm not sure if this is related
#31695

also there are efforts vom Jia but it seemed that this did not find its way into Angular
angular/zone.js#1011

[JoostK]

This is indeed essentially the same as #31695; ResizeObserver is not patched by zone.js and therefore requires manually entering the zone within the resize callback.

[Timebutt]

Hi @JoostK, I'm just running into this exact same issue in some code I'm developing and started digging into code. I did indeed find out that the ResizeObserver is not patched by default by zone.js, but oddly enough there is an implementation for just that present in the zone.js codebase.

If I add an import 'zone.js/dist/zone-patch-resize-observer'; to my polyfills.ts, the ResizeObserver callback is correctly patched as I would expect, and needs no explicit zone.run() anymore. Furthermore, if I add below code to zone.js:

Zone.__load_patch('ResizeObserver', (global: any, Zone: ZoneType, api: _ZonePrivate) => {
  patchClass('ResizeObserver');
});

similar to the implementation here, it also just works.

I'm trying to understand why that code is provisioned if it isn't used by default? Is there a reasoning in which we incur a performance hit by patching ResizeObserver using the existing implementation and so applying the patch is left to the developer in need, or is this just an oversight and as such a bug in zone.js?

[JoostK]

I don't know, TBH. Maybe @JiaLiPassion recalls.

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