What signals actually did to Angular lifecycle hooks

You cannot replace every Angular lifecycle hook with a signal, and that is the interesting part.

Two of the eight hooks aren’t replaced by signals at all.

Let’s start with what’s actually in the framework. I checked @angular/core@22.1.2 and all eight lifecycle interfaces are still exported. Not one of them is marked deprecated. They all live in a single file, packages/core/src/change_detection/lifecycle_hooks.ts, pinned here to the v22.1.2 tag:

• OnChanges

• OnInit

• DoCheck

• OnDestroy

• AfterContentInit

• AfterContentChecked

• AfterViewInit

• AfterViewChecked

I built a small app where each hook’s old and new version sit side by side, and I’ll point at it as we go. I also managed to write a genuinely bad bug in that app, which turned out to be the best part of the exercise.