owltide/shared/utils/update.ts

import type { ApiEntity, ApiTombstone } from "~/shared/types/api";

export function applyUpdatesToArray<T extends ApiEntity | ApiTombstone>(updates: T[], entities: T[]) {
	const idMap = new Map(entities.map((e, i) => [e.id, i]));
	for (const update of updates) {
		const index = idMap.get(update.id);
		if (index !== undefined) {
			entities[index] = update;
		} else {
			idMap.set(update.id, entities.length);
			entities.push(update);
		}
	}
}