Angular calls a set of lifecycle hook methods on components and directives at specific moments — during creation, every change detection cycle, and finally before destruction. Implementing the corresponding interface (e.g. OnInit, OnDestroy) is optional but recommended for type safety.
1. constructor vs. ngOnInit
The constructor is a TypeScript feature, not an Angular lifecycle hook. Angular calls it before inputs are set, so @Input() values are undefined at that point.
@Component({ selector: 'app-card', template: '' })
export class CardComponent implements OnInit {
