DoCheck class abstract

Implement to execute ngDoCheck and implement your own change detection.

By default, AngularDart does an identity based change detection of all input bindings (@Input()). That is, for an @Input() Object a, if the expression identical(oldA, newA) is false, AngularDart will invoke comp.a = newA (and call AfterChanges.ngAfterChanges, if implemented).

When DoCheck is implemented, AngularDart will invoke ngDoCheck() every time the component was checked for changes, regardless of whether the identity of an @Input() has changed, giving the user the opportunity to perform manual checks for mutations.

The ngDoCheck lifecylce is used by NgFor, NgStyle and NgClass, for example, in order to update when the contents of the passed in collection (either Iterable or Map) changes, not necessarily just if the identity changes.

WARNING: It is invalid to trigger any asynchronous event in ngDoCheck. Doing so may cause an infinite loop, as DoCheck will continue to be called and the asynchronous events will invalidate the state.

WARNING: It is invalid to implement both DoCheck and OnChanges or AfterChanges. ngOnChanges and ngAfterChanges will never be called, as ngDoCheck is used instead of the default change detector.