IndexedDB API 的 IDBOpenDBRequest 接口提供了访问打开或删除数据库的请求的结果(通过调用 and IDBFactory.deleteDatabase),途径就是使用特殊的事件处理器属性。


此特性在 Web Worker 中可用。


Also inherits methods from its parents IDBRequest and EventTarget.



The event handler for the blocked event. This event is triggered when the upgradeneeded event should be triggered because of a version change but the database is still in use (i.e. not closed) somewhere, even after the versionchange event was sent.
upgradeneeded 事件的事件处理器,会在当一个数据库的版本比已经存在的版本还高的时候触发。

No methods, but inherits methods from its parents IDBRequest and EventTarget.


In the following example you can see the onupgradeneeded handler being used to update the database structure if a database with a higher version number is loaded. For a full working example, see our To-do Notifications app (view example live.)

var db;

// Let us open our database
var DBOpenRequest ="toDoList", 4);

// these event handlers act on the database being opened.
DBOpenRequest.onerror = function(event) {
  note.innerHTML += '<li>Error loading database.</li>';

DBOpenRequest.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 = DBOpenRequest.result;

  // Run the displayData() function to populate the task
  // listwith all the to-do list data already in the IDB

// 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 line above
// it is only implemented in recent browsers
DBOpenRequest.onupgradeneeded = function(event) {
  var db = this.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" });

  // define what data items the objectStore will contain

  objectStore.createIndex("hours", "hours", { unique: false });
  objectStore.createIndex("minutes", "minutes", { unique: false });
  objectStore.createIndex("day", "day", { unique: false });
  objectStore.createIndex("month", "month", { unique: false });
  objectStore.createIndex("year", "year", { unique: false });
  objectStore.createIndex("notified", "notified", { unique: false });


Specification Status Comment
Indexed Database API 2.0
Recommendation Initial definition
Indexed Database API 2.0

Browser compatibility

BCD tables only load in the browser

See also