Property 'orderBy' does not exist on type 'AngularFirestoreCollection<DocumentData>
this.announcementCollectionRef = afs.collection<Announcement>('announcements', ref => ref.orderBy('createdAt', 'desc'));
this.announcements = this.announcementCollectionRef.snapshotChanges().map(actions => {
return actions.map(a => {
const data = a.payload.doc.data() as AnnouncementId;
const id = a.payload.doc.id;
return { id, ...data };
});
});