app.componen.ts file:
class AppComponent {

}

//Export the class from the outside of the file
export class AppComponent {
    //name: title; field: string
    title: string = 'app'; 
    title = 'app';
    items: stringp[] = ['item 1', 'item 2'];
}


//TypeScript Array Field
export class AppComponent {
    log(text: string): void { 
        var message: string = 'Message' + text;
        console.log(message);
    }
    //public by default
    private log(text: string) : void {...}
    items = ['item 1', 'item 2'];

    f() {
        this.log(...);
        this.items...
    }
}

var a: number[]
var a: string[]
var a: boolean[]
var app: AppComponent[]

@Component({...})
export class AppComponent{

}

@Component({
    selector: 'app-root',
    templateUrl: './app.component.html'
})
export class AppComponent {

}