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The index() method of the IDBObjectStore interface opens a named index in the current object store, after which it can be used to, for example, return a series of records sorted by that index using a cursor. 

Note: This feature is available in Web Workers.


var index = objectStore.index(name);


The name of the index to open.

Return value

An IDBIndex object for accessing the index.


This method may raise a DOMException of one of the following types:

Exception Description
InvalidStateError The source object store has been deleted, or the transaction for the object store has finished.
NotFoundError There is no index with the given name (case-sensitive) in the database.


In the following example we open a transaction and an object store, then get the index lName from a simple contacts database. We then open a basic cursor on the index using IDBIndex.openCursor — this works the same as opening a cursor directly on an ObjectStore using IDBObjectStore.openCursor except that the returned records are sorted based on the index, not the primary key.

Finally, we iterate through each record, and insert the data into an HTML table. For a complete working example, see our IDBIndex-example demo repo (View the example live.)

function displayDataByIndex() {
  tableEntry.innerHTML = '';
  var transaction = db.transaction(['contactsList'], 'readonly');
  var objectStore = transaction.objectStore('contactsList');

  var myIndex = objectStore.index('lName'); 
  myIndex.openCursor().onsuccess = function(event) {
    var cursor =;
    if(cursor) {
      var tableRow = document.createElement('tr');
      tableRow.innerHTML =   '<td>' + + '</td>'
                           + '<td>' + cursor.value.lName + '</td>'
                           + '<td>' + cursor.value.fName + '</td>'
                           + '<td>' + cursor.value.jTitle + '</td>'
                           + '<td>' + + '</td>'
                           + '<td>' + cursor.value.eMail + '</td>'
                           + '<td>' + + '</td>'
                           + '<td>' + cursor.value.age + '</td>';

    } else {
      console.log('Entries all displayed.');    


Specification Status Comment
Indexed Database API
The definition of 'index()' in that specification.
Indexed Database API 2.0
The definition of 'index()' in that specification.
Editor's Draft  

Browser compatibility

Feature Chrome Edge Firefox (Gecko) Internet Explorer Opera Safari (WebKit)
Basic support 23webkit
(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, inexorabletash, chrisdavidmills, fscholz
 Last updated by: jpmedley,