IDBFactory.open() - Web APIs 编辑

The open() method of the IDBFactory interface requests opening a connection to a database.

The method returns an IDBOpenDBRequest object immediately, and performs the open operation asynchronously. If the operation is successful, a success event is fired on the request object that is returned from this method, with its result attribute set to the new IDBDatabase object for the connection.

If an error occurs while the database connection is being opened, then an error event is fired on the request object returned from this method.

May trigger upgradeneeded, blocked or versionchange events.

Note:

Syntax

For the current standard:

var IDBOpenDBRequest = indexedDB.open(name);
var IDBOpenDBRequest = indexedDB.open(name, version);

Parameters

name

The name of the database.

version Optional

Optional. The version to open the database with. If the version is not provided and the database exists, then a connection to the database will be opened without changing its version. If the version is not provided and the database does not exist, then it will be created with version 1.

Experimental Gecko options object

options (version and storage) Optional

In Gecko, since version 26, you can include a non-standard options object as a parameter of IDBFactory.open that contains the version number of the database, plus a storage value that specifies whether you want to use persistent or temporary storage. Warning: The storage attribute is deprecated and will soon be removed from Gecko. You should use StorageManager.persist() to get persistent storage instead.

Note: You can find out more information on the different available storage types, and how Firefox handles client-side data storage, at Browser storage limits and eviction criteria.

Return value

A IDBOpenDBRequest object on which subsequent events related to this request are fired.

Exceptions

This method may raise a DOMException of the following types:

Example

Example of calling open with the current specification's version parameter:

var request = window.indexedDB.open("toDoList", 4);

In the following code snippet, we make a request to open a database, and include handlers for the success and error cases. 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
• Reference example: To-do Notifications (view example live.)