IDBCursor.direction
The direction
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.
Syntax
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
Specification | Status | Comment |
---|---|---|
Indexed Database API The definition of 'direction' 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/idbcursor/direction