The update()
method of the IDBCursor
interface returns an IDBRequest
object, and, in a separate thread, updates the value at the current position of the cursor in the object store. If the cursor points to a record that has just been deleted, a new record is created.
Be aware that you can't call update()
(or IDBCursor.delete()
) on cursors obtained from IDBIndex.openKeyCursor()
. For such needs, you have to use IDBIndex.openCursor()
instead.
Syntax
var anIDBRequest = myIDBCursor.update(value);
Parameters
- value
- The new value to be stored at the current position.
Return value
An IDBRequest
object on which subsequent events related to this operation are fired.
Exceptions
This method may raise a DOMException
of one of the following types:
Exception | Description |
---|---|
TransactionInactiveError |
This IDBCursor's transaction is inactive. |
ReadOnlyError |
The transaction mode is read only. |
InvalidStateError |
The cursor was created using IDBIndex.openKeyCursor , is currently being iterated, or has iterated past its end. |
DataError |
The underlying object store uses in-line keys and the property in the value at the object store's key path does not match the key in this cursor's position. |
DataCloneError |
The data being stored could not be cloned by the internal structured cloning algorithm. |
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. If the albumTitle
of the current cursor is "A farewell to kings", we update year the album was released using var request = cursor.update();
.
Note that you cannot change primary keys using cursor.update()
, hence us not changing the album title; this would ruin the integrity of the data. In such a situation, you would have to delete the record altogether and then add a new one using IDBObjectStore.add
. Note also that you can't directly put cursor.value
into an update call, hence the below example using an intermediary updateData
variable.
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 updateResult() { list.innerHTML = ''; const transaction = db.transaction(['rushAlbumList'], 'readwrite'); const objectStore = transaction.objectStore('rushAlbumList'); objectStore.openCursor().onsuccess = function(event) { const cursor = event.target.result; if (cursor) { if (cursor.value.albumTitle === 'A farewell to kings') { const updateData = cursor.value; updateData.year = 2050; const request = cursor.update(updateData); request.onsuccess = function() { console.log('A better album year?'); }; }; const listItem = document.createElement('li'); listItem.innerHTML = '<strong>' + cursor.value.albumTitle + '</strong>, ' + cursor.value.year; list.appendChild(listItem); cursor.continue(); } else { console.log('Entries displayed.'); } }; };
Specifications
Specification | Status | Comment |
---|---|---|
Indexed Database API 2.0 The definition of 'update()' in that specification. |
Recommendation | |
Indexed Database API Draft The definition of 'update()' in that specification. |
Recommendation |
Browser compatibility
Desktop | Mobile | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|
update | Chrome
Full support
24
| Edge Full support 12 | Firefox
Full support
16
| IE Partial support 10 | Opera Full support 15 | Safari Full support 7 | WebView Android Full support Yes | Chrome Android Full support Yes | Firefox Android Full support 22 | Opera Android Full support 14 | Safari iOS Full support 8 | Samsung Internet Android Full support Yes |
Legend
- Full support
- Full support
- Partial support
- Partial support
- Requires a vendor prefix or different name for use.
- Requires a vendor prefix or different name for use.
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.)