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.textContent = ''; const transaction = db.transaction(['rushAlbumList'], 'readonly'); const objectStore = transaction.objectStore('rushAlbumList'); objectStore.openCursor(null,'prev').onsuccess = function(event) { const cursor = event.target.result; if(cursor) { const 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
Desktop | Mobile | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|
Chrome | Edge | Firefox | Internet Explorer | Opera | Safari | WebView Android | Chrome Android | Firefox for Android | Opera Android | Safari on IOS | Samsung Internet | |
direction |
23 |
12 |
10 |
10 |
15 |
7 |
≤37 |
Yes |
22 |
14 |
8 |
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.)
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https://developer.mozilla.org/en-US/docs/Web/API/IDBCursor/direction