Apr 24, 2020 · Angular For Beginners Guide - Components vs Directives Last Updated: 24 April 2020 local_offer Angular For Beginners Summary: In this article, you will learn how to extend the browser and build your own custom HTML Input tag, as a means of learning the main functionality provided by Angular Components and Directives. Angular's unidirectional data flow rule prevents updating the parent view's in the same cycle. The app has to wait one turn before it can display the seconds. Use setTimeout () to wait one tick and then revise the seconds () method so that it takes future values from the timer component. Test it link. Sep 28, 2019 · Angular also performs default change-detection an invokes ngOnChanges () callback which is the method of OnChanges lifecycle hook. The ngDoCheck () callback method is run after ngOnChanges () callback method. According to Angular doc, we should not use both ngDoCheck () and ngOnChanges () callback methods to respond to changes on the same input.