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/DOM

IDBCursor.direction

The direction read-only property of the IDBCursor interface is a DOMString that returns the direction of traversal of the cursor (set using IDBObjectStore.openCursor for example). See the Values section below for possible values.

Note: This feature is available in Web Workers.

Syntax

var direction = cursor.direction;

Value

A string (defined by the IDBCursorDirection enum) indicating the direction in which the cursor is traversing the data. Possible values are:

Value Description
next This direction causes the cursor to be opened at the start of the source.
nextunique This direction causes the cursor to be opened at the start of the source. For every key with duplicate values, only the first record is yielded.
prev This direction causes the cursor to be opened at the end of the source.
prevunique This direction causes the cursor to be opened at the end of the source. For every key with duplicate values, only the first record is yielded.

Example

In this simple fragment we create a transaction, retrieve an object store, then use a cursor to iterate through all the records in the object store. Within each iteration we log the direction of the cursor, something like this:

prev

Note: we can't change the direction of travel of the cursor using the direction property, as it is read-only. We specify the direction of travel using the 2nd argument of IDBObjectStore.openCursor.

The cursor does not require us to select the data based on a key; we can just grab all of it. Also note that in each iteration of the loop, you can grab data from the current record under the cursor object using cursor.value.foo. For a complete working example, see our IDBCursor example (view example live.)

function backwards() {
  list.innerHTML = '';
  var transaction = db.transaction(['rushAlbumList'], 'readonly');
  var objectStore = transaction.objectStore('rushAlbumList');

  objectStore.openCursor(null,'prev').onsuccess = function(event) {
    var cursor = event.target.result;
      if(cursor) {
        var listItem = document.createElement('li');
        listItem.innerHTML = '<strong>' + cursor.value.albumTitle + '</strong>, ' + cursor.value.year;
        list.appendChild(listItem);  
          
        console.log(cursor.direction);
        cursor.continue();
      } else {
        console.log('Entries displayed backwards.');
      }
  };
};

Specifications

Browser compatibility

Feature Chrome Edge Firefox (Gecko) Internet Explorer Opera Safari (WebKit)
Basic support 23webkit
24
(Yes) 10 moz
16.0 (16.0)
10, partial 15 7.1
Available in workers (Yes) (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) (Yes) 37.0 (37.0) (Yes) ? (Yes) ?
Indexed Database 2.0 58 58 ? ? ? ? 45 ?

See also

© 2005–2018 Mozilla Developer Network and individual contributors.
Licensed under the Creative Commons Attribution-ShareAlike License v2.5 or later.
https://developer.mozilla.org/en-US/docs/Web/API/IDBCursor/direction