IDBVersionChangeEvent - Web APIs 编辑

The IDBVersionChangeEvent interface of the IndexedDB API indicates that the version of the database has changed, as the result of an IDBOpenDBRequest.onupgradeneeded event handler function.

Note:

Properties

Also inherits properties from its parent, Method.

IDBVersionChangeEvent.oldVersion Read only

Returns the old version of the database.

IDBVersionChangeEvent.newVersion Read only

Returns the new version of the database.

Deprecated properties

IDBVersionChangeEvent.version Read only

The new version of the database in a versionchange transaction.

Warning: While this property is still implemented in older browsers, the latest specification replaces it with the oldVersion and newVersion attributes. See the compatibility table to know what browsers support them.

Methods

No specific method, but inherits properties from its parent, Method.

Example

In the following code snippet, we make a request to open a database, and include handlers for the success and error cases. Upon a version change (after an upgradedneeded event), the success event will implement the IDBVersionChangeEvent interface. For a full working example, see our To-do Notifications app (view example live.)

var note = document.querySelector("ul");

// In the following line, you should include the prefixes of implementations you want to test.
window.indexedDB = window.indexedDB || window.mozIndexedDB || window.webkitIndexedDB || window.msIndexedDB;
// DON'T use "var indexedDB = ..." if you're not in a function.
// Moreover, you may need references to some window.IDB* objects:
window.IDBTransaction = window.IDBTransaction || window.webkitIDBTransaction || window.msIDBTransaction;
window.IDBKeyRange = window.IDBKeyRange || window.webkitIDBKeyRange || window.msIDBKeyRange;
// (Mozilla has never prefixed these objects, so we don't need window.mozIDB*)

// Let us open version 4 of our database
var DBOpenRequest = window.indexedDB.open("toDoList", 4);

// these two event handlers act on the database being opened successfully, or not
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 later on, for opening transactions and suchlike.
  db = DBOpenRequest.result;
};

Specifications

Browser compatibility

BCD tables only load in the browser

See also

• Using IndexedDB
• Starting transactions: IDBDatabase
• Using transactions: IDBTransaction
• Setting a range of keys: IDBKeyRange
• Retrieving and making changes to your data: IDBObjectStore
• Using cursors: IDBCursor
• IDBDatabase.onversionchange
• Reference example: To-do Notifications (view example live.)