example

const NotifReconciler = new NotificationReconciler();

// add some notification to schedule 

NotifReconciler.process([
  new MyNotification({ date: "01/01/2018", message: "Hello World", id: 1 }),
  new MyNotification({ date: "01/02/2018", message: "Hello World2", id: 2 }),
]);

// second notification not needed now
// it will cancel only second

NotifReconciler.process([
  new MyNotification({ date: "01/01/2018", message: "Hello World", id: 1 }),
]);

notification-declarative.ts

// simple array diff algo with O(2m+n) complexity
const arraysDiff = (first, second, key) => {
	const keysInFirst = first.reduce((acc, item) => {
		if (item == null) {
			return acc;
		}

		const id = item[key];

		acc[id] = item;

		return acc;
	}, {});

	const added = second.reduce((acc, item) => {
		if (item == null) {
			return acc;
		}

		const id = item[key];
		const isExist = keysInFirst[id];

		if (isExist != null) {
			keysInFirst[id] = null;
		} else {
			acc.push(item);
		}

		return acc;
	}, []);

	const removed = Object.keys(keysInFirst).reduce((acc, key) => {
		const item = keysInFirst[key];
		if (item == null) {
			return acc;
		}

		acc.push(item);

		return acc;
	}, []);

	return {
		removed,
		added,
	};
};

export class NotificationReconciler {

	savedNotifications: Array<Notification> = [];
	static storageKey: string = 'Notifications';
	private persistanceState: ReconcilerPersistanceState = ReconcilerPersistanceState.empty;

	process(newNotifications: Array<Notification>): void {
		const { removed, added } = arraysDiff(this.savedNotifications, newNotifications, 'id');

		added.forEach((item: Notification) => {
			if (item == null) {
				return;
			}

			this.add(item);
		});

		removed.forEach(item => {
			if (item == null) {
				return;
			}

			this.remove(item);
		});

		this.saveNewNotifications(newNotifications);
	}

	private add(notification: Notification): void {
		this.pushNotification.localNotificationSchedule({
			date: notification.date,
			message: notification.message,
			userInfo: { id: notification.id },
		});
	}

	private remove(notification: Notification): void {
		this.pushNotification.cancelLocalNotifications({ id: notification.id });
	}

	private saveNewNotifications(notifications: Array<Notification>): void {
		this.savedNotifications = notifications;
		this.storage.setItem(
			NotificationReconciler.storageKey,
			JSON.stringify(notifications.filter(it => it != null).map(({ id }) => ({ id })))
		);
	}
}