Promise-Based IndexedDB Key-Value Store

const databaseName = 'app-cache';
const storeName = 'key-value';

function openDatabase(): Promise<IDBDatabase> {
  return new Promise((resolve, reject) => {
    const request = indexedDB.open(databaseName, 1);

    request.addEventListener('upgradeneeded', () => {
      const database = request.result;

      if (!database.objectStoreNames.contains(storeName)) {
        database.createObjectStore(storeName);
      }
    });

    request.addEventListener('success', () => {
      resolve(request.result);
    });

    request.addEventListener('error', () => {
      reject(request.error);
    });
  });
}

export async function setValue<T>(
  key: IDBValidKey,
  value: T,
): Promise<void> {
  const database = await openDatabase();

  await new Promise<void>((resolve, reject) => {
    const transaction = database.transaction(
      storeName,
      'readwrite',
    );

    transaction.objectStore(storeName).put(value, key);
    transaction.addEventListener('complete', () => resolve());
    transaction.addEventListener('error', () => reject(transaction.error));
  });

  database.close();
}