IndexedDB 版本迁移与零停机升级

`title: IndexedDB 版本迁移与零停机升级``categories: Web 开发/前端/数据管理``keywords: IndexedDB,版本迁移,onupgradeneeded,零停机,兼容``description: 设计安全的 IndexedDB 版本迁移流程，采用幂等与向后兼容策略，实现零停机升级与平滑演进。`迁移策略幂等创建与更新对象仓库与索引，存在则跳过。小步快跑：多次小版本演进，避免大爆炸迁移。实现示例function openDB(name = 'app', version = 3) { return new Promise((resolve, reject) => { const req = indexedDB.open(name, version); req.onupgradeneeded = () => { const db = req.result; if (!db.objectStoreNames.contains('items')) { db.createObjectStore('items', { keyPath: 'id' }); } const store = req.transaction.objectStore('items'); if (!store.indexNames.contains('byCreatedAt')) store.createIndex('byCreatedAt', 'createdAt'); if (!store.indexNames.contains('byOwner')) store.createIndex('byOwner', 'owner'); }; req.onsuccess = () => resolve(req.result); req.onerror = () => reject(req.error); }); } 版本变更处理监听 `onversionchange`，提示刷新或自动重连；迁移完成后恢复业务。