autostore.ts

/*
  This svelte store is a reference to make super quick live and interactive pieces of code. 
  See its announcement at https://www.youtube.com/watch?v=A8jkJTWacow&t=18579s
*/

type Options<T> = {
	validator: (data: T) => void;
};

export function live<T>(path: string, initialValue: T, options?: Options<T>) {
	const store = writable(initialValue, (set) => {
		let unsubscribe = onDbChange((newData) => {
			try {
				options?.validator?.(newData);
			} catch (e) {
				console.warn('Data from remote is invalid');
				console.error(e);
			}
			set(newData);
		});

		return unsubscribe;
	});

	const { subscribe, set } = store;

	return {
		set(newData: T) {
			options?.validator?.(newData);
			set(newData);
		},
		save() {
			const data = get(store);
			updateDb(path, data);
		},
		subscribe
	};
}

What do you think about invoking updateDb automatically in the returned set function? Probably on a debounce or something similar

Totally possible! Could automatically save to the database after debounce. Might be a bit dangerous though. Be careful not to cause extra writes — perhaps deep object comparison could be implemented in the set method.