Angular: Componentful Functions

function-works.component.ts

@Component({
  selector: 'app-function-works',
  templateUrl: './function-works.component.html',
  styleUrls: ['./function-works.component.css']
})
export class FunctionWorksComponent implements OnInit {
  message = 'foo';

  constructor() { }

  ngOnInit() {
    this.message = 'bar';
  }

  sayHello() {
    this.message = 'Hello World';
  }
}