在此页

• 句法
• 范例
• 规范
• 浏览器兼容性
• 另请参阅
• 相关话题

onblocked event handler of the IDBOpenDBRequest interface is the event handler for the blocked event. This event is triggered when the upgradeneeded should be triggered because of a version change but the database is still in use (that is, not closed) somewhere, even after the versionchange event was sent.

注意： 此特征可用于 Web 工作者 .

句法

IDBOpenDBRequest.onblocked = function(event) { ... };
					

范例

var db;
// Let us open our database
var request = indexedDB.open("toDoList", 4);
// these two event handlers act on the database being opened
// successfully, or not
request.onerror = function(event) {
  note.innerHTML += '<li>Error loading database.</li>';
};
request.onsuccess = function(event) {
  note.innerHTML += '<li>Database initialised.</li>';
  // store the result of opening the database in the db variable.
  // This is used a lot below
  db = request.result;
  // Run the displayData() function to populate the task list with
  // all the to-do list data already in the IDB
  displayData();
};
// This event handles the event whereby a new version of the
// database needs to be created. Either one has not been created
// before, or a new version number has been submitted via the
// window.indexedDB.open line above
//it is only implemented in recent browsers
request.onupgradeneeded = function(event) {
  var db = event.target.result;
  db.onerror = function(event) {
    note.innerHTML += '<li>Error loading database.</li>';
  };
  // Create an objectStore for this database
  var objectStore = db.createObjectStore("toDoList", { keyPath: "taskTitle" });
  ...
};
request.onblocked = function() {
  console.log("Your database version can't be upgraded because the app is open somewhere else.");
}
					

规范

规范	状态	注释
索引数据库 API 2.0 The definition of 'onblocked' in that specification.	推荐
索引数据库 API 草案 The definition of 'onblocked' in that specification.	推荐

浏览器兼容性

The compatibility table on this page is generated from structured data. If you'd like to contribute to the data, please check out https://github.com/mdn/browser-compat-data and send us a pull request. 更新 GitHub 上的兼容性数据

	桌面						移动
	Chrome	Edge	Firefox	Internet Explorer	Opera	Safari	Android webview	Chrome for Android	Firefox for Android	Opera for Android	Safari on iOS	Samsung Internet
onblocked	Chrome 24 24 不支持 23 — 57 Prefixed Prefixed Implemented with the vendor prefix: webkit	Edge 12	Firefox 16 16 不支持 10 — 16 Prefixed Prefixed Implemented with the vendor prefix: moz	IE 部分支持 10	Opera 15	Safari 7	WebView Android Yes Yes 不支持 ? — 57 Prefixed Prefixed Implemented with the vendor prefix: webkit	Chrome Android 25 25 不支持 25 — 57 Prefixed Prefixed Implemented with the vendor prefix: webkit	Firefox Android 22	Opera Android 14	Safari iOS 8	Samsung Internet Android 1.5 1.5 不支持 1.5 — 7.0 Prefixed Prefixed Implemented with the vendor prefix: webkit

图例

完整支持

完整支持

部分支持

部分支持

要求使用供应商前缀或不同名称。

要求使用供应商前缀或不同名称。

另请参阅

• 使用 IndexedDB
• 开始事务： IDBDatabase
• 使用事务： IDBTransaction
• 设置一系列键： IDBKeyRange
• 检索并使您的数据改变： IDBObjectStore
• 使用光标： IDBCursor
• 参考范例： 待办通知 ( 实时查看范例 )。
• blocked event

元数据

• 最后修改： 2020 年 1 月 22 日

相关话题

1. IndexedDB API
2. IDBOpenDBRequest
3. 特性

   1. onblocked
   2. onupgradeneeded
4. 事件

   1. blocked
   2. upgradeneeded
5. 继承：

   1. IDBRequest
   2. EventTarget
6. IndexedDB 相关页面

   1. IDBCursor
   2. IDBCursorSync
   3. IDBCursorWithValue
   4. IDBDatabase
   5. IDBDatabaseException
   6. IDBDatabaseSync
   7. IDBEnvironment
   8. IDBEnvironmentSync
   9. IDBFactory
   10. IDBFactorySync
   11. IDBIndex
   12. IDBIndexSync
   13. IDBKeyRange
   14. IDBObjectStore
   15. IDBObjectStoreSync
   16. IDBRequest
   17. IDBTransaction
   18. IDBTransactionSync
   19. IDBVersionChangeEvent
   20. IDBVersionChangeRequest