import {
 collection,
 collectionData,
 Firestore,
 limit,
 orderBy,
 query,
 startAfter
} from "@angular/fire/firestore";
querySnapshot:any;
lastInResponse:any;
 constructor( private stringEmitted: StringBridgeService, private firestore: Firestore ) {
 }
 ngOnInit(): void {
 this.stringEmitted.stringChanged(this.actualTitle);
 this.loadCustomers('customers', 'name', 5)
 }
 loadCustomers(collectionName:string, order:string, max:number) {
 return collectionData(query(collection(this.firestore, collectionName), orderBy(order), limit(max))).subscribe(
 response => {
 this.lastInResponse = response[response.length - 1];
 this.querySnapshot = response;
 }
 );
 }
 loadMore(data:any) {
 if(this.lastInResponse){
 return collectionData(query(collection(this.firestore, 'customers'), orderBy('name'), limit(3), startAfter(data['name']))).subscribe(
 response => {
 this.lastInResponse = response[response.length - 1];
 this.querySnapshot = this.querySnapshot.concat(response);
 // this.querySnapshot = response;
 }
 );
 }
 return null
 }
 myTest() {
 console.log(this.lastInResponse);
 }