The key
read-only property of the IDBCursor
interface 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.
Syntax
var key = cursor.key;
Value
A value of any type.
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 key of the cursor to the console, something like this (its the album title in each case, which is our key).
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);
console.log(cursor.key);
cursor.continue();
} else {
console.log('Entries all displayed.');
}
};
};
Specifications
Specification | Status | Comment |
---|---|---|
Indexed Database API 2.0 The definition of 'key' in that specification. |
Recommendation | |
Indexed Database API Draft The definition of 'key' in that specification. |
Recommendation |
Browser compatibility
Desktop | Mobile | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|
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 |
Binary keys | 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 ? | Opera Android Full support 43 | Safari iOS Full support 10.3 | Samsung Internet Android Full support 7.0 |
Legend
- Full support
- Full support
- Partial support
- Partial 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.)