MDN will switch to a new design later today, a sneak peek: https://blog.mozilla.org/opendesign/mdns-new-design-beta/

The 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.

Note: This feature is available in Web Workers.

Syntax

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

Example

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.
Recommendation  
Indexed Database API 2.0
The definition of 'onblocked' in that specification.
Editor's Draft  

Browser compatibility

Feature Chrome Edge Firefox (Gecko) Internet Explorer Opera Safari (WebKit)
Basic support 23webkit
24 (unprefixed)
(Yes) 10 moz
16.0 (16.0)
10, partial 15 7.1
Available in workers (Yes) ? 37.0 (37.0) ? (Yes) ?
Indexed Database 2.0 58 ? ? ? 45 ?
Feature Android Webview Chrome for Android Edge Firefox Mobile (Gecko) Firefox OS IE Phone Opera Mobile Safari Mobile
Basic support (Yes) (Yes) (Yes) 22.0 (22.0) 1.0.1 10 22 8
Available in workers (Yes) (Yes) ? 37.0 (37.0) (Yes) ? (Yes) ?
Indexed Database 2.0 58 58 ? ? ? ? 45 ?

See also

Document Tags and Contributors

 Contributors to this page: jpmedley, libbymc, chrisdavidmills, teoli, eharris, fscholz, eicto
 Last updated by: jpmedley,