Note: Not to be confused with IDBCursorWithValue
which is just an IDBCursor
interface with an additional value
property.
The IDBCursor
interface of the IndexedDB API represents a cursor for traversing or iterating over multiple records in a database.
The cursor has a source that indicates which index or object store it is iterating over. It has a position within the range, and moves in a direction that is increasing or decreasing in the order of record keys. The cursor enables an application to asynchronously process all the records in the cursor's range.
You can have an unlimited number of cursors at the same time. You always get the same IDBCursor
object representing a given cursor. Operations are performed on the underlying index or object store.
Properties
Note: IDBCursorWithValue
is an IDBCursor
interface with an additional value
property.
IDBCursor.source
Read only- Returns the
IDBObjectStore
orIDBIndex
that the cursor is iterating. This function never returns null or throws an exception, even if the cursor is currently being iterated, has iterated past its end, or its transaction is not active. IDBCursor.direction
Read only- Returns the direction of traversal of the cursor. See Constants for possible values.
IDBCursor.key
Read only- Returns the key for the record at the cursor's position. If the cursor is outside its range, this is set to
undefined
. The cursor's key can be any data type. IDBCursor.primaryKey
Read only- Returns the cursor's current effective primary key. If the cursor is currently being iterated or has iterated outside its range, this is set to
undefined
. The cursor's primary key can be any data type. IDBCursor.request
Read only- Returns the
IDBRequest
that was used to obtain the cursor.
Methods
IDBCursor.advance()
- Sets the number of times a cursor should move its position forward.
IDBCursor.continue()
- Advances the cursor to the next position along its direction, to the item whose key matches the optional
key
parameter. IDBCursor.continuePrimaryKey()
- Sets the cursor to the given index key and primary key given as arguments.
IDBCursor.delete()
- Returns an
IDBRequest
object, and, in a separate thread, deletes the record at the cursor's position, without changing the cursor's position. This can be used to delete specific records. IDBCursor.update()
- Returns an
IDBRequest
object, and, in a separate thread, updates the value at the current position of the cursor in the object store. This can be used to update specific records.
Constants
Deprecated since Gecko 13 (Firefox 13 / Thunderbird 13 / SeaMonkey 2.10)
This feature is no longer recommended. Though some browsers might still support it, it may have already been removed from the relevant web standards, may be in the process of being dropped, or may only be kept for compatibility purposes. Avoid using it, and update existing code if possible; see the compatibility table at the bottom of this page to guide your decision. Be aware that this feature may cease to work at any time.
These constants are no longer available — they were removed in Gecko 25. You should use the string constants directly instead. (bug 891944)
NEXT
:"next"
: The cursor shows all records, including duplicates. It starts at the lower bound of the key range and moves upwards (monotonically increasing in the order of keys).NEXTUNIQUE
:"nextunique"
: The cursor shows all records, excluding duplicates. If multiple records exist with the same key, only the first one iterated is retrieved. It starts at the lower bound of the key range and moves upwards.PREV
:"prev"
: The cursor shows all records, including duplicates. It starts at the upper bound of the key range and moves downwards (monotonically decreasing in the order of keys).PREVUNIQUE
:"prevunique"
: The cursor shows all records, excluding duplicates. If multiple records exist with the same key, only the first one iterated is retrieved. It starts at the upper bound of the key range and moves downwards.
Examples
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. 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 displayData() { var transaction = db.transaction(['rushAlbumList'], "readonly"); var objectStore = transaction.objectStore('rushAlbumList'); objectStore.openCursor().onsuccess = function(event) { var cursor = event.target.result; if(cursor) { var listItem = document.createElement('li'); listItem.innerHTML = cursor.value.albumTitle + ', ' + cursor.value.year; list.appendChild(listItem); cursor.continue(); } else { console.log('Entries all displayed.'); } }; }
Specifications
Specification | Status | Comment |
---|---|---|
Indexed Database API 2.0 The definition of 'cursor' in that specification. |
Recommendation | Initial definition |
Indexed Database API Draft The definition of 'cursor' in that specification. |
Recommendation | Added continuePrimaryKey() and support for binary keys, and the IDBCursor.request property. |
Browser compatibility
Desktop | Mobile | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|
IDBCursor | Chrome
Full support
24
| Edge Full support 12 | Firefox
Full support
16
| IE Partial support 10 | Opera
Full support
44
| Safari Full support 7 | WebView Android
Full support
Yes
| Chrome Android
Full support
25
| Firefox Android Full support 22 | Opera Android
Full support
43
| Safari iOS Full support 8 | Samsung Internet Android
Full support
1.5
|
advance | 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 |
continue | 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 |
continuePrimaryKey | Chrome Full support 58 | Edge Full support 79 | Firefox
Full support
51
| IE ? | Opera Full support 45 | Safari Full support 10.1 | WebView Android Full support 58 | Chrome Android Full support 58 | Firefox Android Full support 51 | Opera Android Full support 43 | Safari iOS Full support 10.3 | Samsung Internet Android Full support 7.0 |
delete | 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 |
direction | 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 |
key | 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 |
primaryKey | 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 |
request | Chrome Full support 76 | Edge Full support 79 | Firefox Full support 77 | IE No support No | Opera Full support 63 | Safari ? | WebView Android Full support 76 | Chrome Android Full support 76 | Firefox Android No support No | Opera Android Full support 54 | Safari iOS ? | Samsung Internet Android Full support 12.0 |
source | 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 |
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 |
Available in workers | Chrome
Full support
24
| Edge Full support ≤18 | Firefox Full support 37 | IE ? | Opera
Full support
44
| Safari Full support 7 | WebView Android
Full support
Yes
| Chrome Android
Full support
25
| Firefox Android Full support 37 | Opera Android
Full support
Yes
| Safari iOS ? | Samsung Internet Android
Full support
1.5
|
Legend
- Full support
- Full support
- Partial support
- Partial support
- No support
- No support
- Compatibility unknown
- Compatibility unknown
- 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.)