使用promise将回调方式变为同步等待方式

应用场景：需同步获取值的时候，回调方式使用起来比较难受，并且库里内并未提供同步api，此时可使用promise+await将回调方式改为同步执行，

核心：promise+await将回调改为同步调用

 const result = await new Promise((resolve, reject) => {request.onsuccess = () => resolve(request.result);request.onerror = () => reject(false);});

原始代码：

// 通用方法 - 获取数据
export async function getCache(key) {const database = await initDB();return new Promise((resolve, reject) => {const tx = database.transaction('apiCache', 'readonly');const store = tx.objectStore('apiCache');const request = store.get(key);request.onsuccess = () => {const result = request.result;if (!result) {resolve(null); // 数据不存在return;}// 检查数据是否过期if (result.expiry < Date.now()) {deleteCache(key); // 删除过期数据resolve(null);} else {resolve(result.data);}};request.onerror = () => {reject(request.error); // 处理错误};});
}

优化后的代码：

// 通用方法 - 获取数据
export async function getCache(key) {const database = await initDB();const tx = database.transaction('apiCache', 'readonly');const store = tx.objectStore('apiCache');const request = await store.get(key);// 将 IndexedDB 请求封装为 Promiseconst result = await new Promise((resolve, reject) => {request.onsuccess = () => resolve(request.result);request.onerror = () => reject(false);});if (!result) {return null;}// 检查数据是否过期if (result.expiry < Date.now()) {await deleteCache(key); // 删除过期数据return null;}return result.data;
}