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.
var direction = cursor.direction;
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. |
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.'); } }; };
Specification | Status | Comment |
---|---|---|
Indexed Database API The definition of 'direction' in that specification. | Recommendation | |
Indexed Database API 2.0 The definition of 'direction' in that specification. | Recommendation |
Desktop | ||||||
---|---|---|---|---|---|---|
Chrome | Edge | Firefox | Internet Explorer | Opera | Safari | |
Basic support | 24
|
12 | 16
|
10
|
15 | 7 |
Mobile | |||||||
---|---|---|---|---|---|---|---|
Android webview | Chrome for Android | Edge Mobile | Firefox for Android | Opera for Android | iOS Safari | Samsung Internet | |
Basic support | Yes | Yes | Yes | 22 | 22 | 8 | Yes |
IDBDatabase
IDBTransaction
IDBKeyRange
IDBObjectStore
IDBCursor
© 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