IDBOpenDBRequest.onblocked
The IDBOpenDBRequest.onblocked
event handler 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.
Note: This feature is available in Web Workers.
Syntax
JavaScript
Copy Code
var request = indexedDB.open("toDoList", 4); request.onblocked = function() { ... };
Example
JavaScript
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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."); }
Specifications
Specification | Status | Comment |
---|---|---|
Indexed Database API The definition of 'onblocked' in that specification. |
Editor's Draft |
Browser compatibility
Feature | Chrome | Firefox (Gecko) | Internet Explorer | Opera | Safari (WebKit) |
---|---|---|---|---|---|
Basic support | 23webkit 24 |
10 moz 16.0 (16.0) |
10, partial | 15 | 7.1 |
Available in workers | (Yes) | 37.0 (37.0) | ? | (Yes) | ? |
Feature | Android | Firefox Mobile (Gecko) | Firefox OS | IE Phone | Opera Mobile | Safari Mobile |
---|---|---|---|---|---|---|
Basic support | 4.4 | 22.0 (22.0) | 1.0.1 | 10 | 22 | 8 |
Available in workers | (Yes) | 37.0 (37.0) | (Yes) | ? | (Yes) | ? |
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.)
License
© 2016 Mozilla Contributors
Licensed under the Creative Commons Attribution-ShareAlike License v2.5 or later.
https://developer.mozilla.org/en-us/docs/web/api/idbopendbrequest/onblocked