IDBCursor.advance() - Web APIs 编辑
The advance()
method of the IDBCursor
interface sets the number of times a cursor should move its position forward.
Note:
This feature is available in Web Workers.Syntax
cursor.advance(count);
Parameters
count
- The number of times to move the cursor forward.
Exceptions
This method may raise a DOMException
of one of the following types:
Exception | Description |
---|---|
TransactionInactiveError | This IDBCursor's transaction is inactive. |
TypeError | The value passed into the count parameter was zero or a negative number. |
InvalidStateError | The cursor is currently being iterated or has iterated past its end. |
Example
In this simple fragment we create a transaction, retrieve an object store, then use a cursor to iterate through the records in the object store. Here we use cursor.advance(2)
to jump 2 places forward each time, meaning that only every other result will be displayed. advance()
works in a similar way to IDBCursor.continue
, except that it allows you to jump multiple records at a time, not just always go onto the next record.
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 advanceResult() {
list.textContent = '';
const transaction = db.transaction(['rushAlbumList'], "readonly");
const objectStore = transaction.objectStore('rushAlbumList');
objectStore.openCursor().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);
cursor.advance(2);
} else {
console.log('Every other entry displayed.');
}
};
};
Specifications
Specification | Status | Comment |
---|---|---|
Indexed Database API 2.0 The definition of 'advance()' in that specification. | Recommendation | |
Indexed Database API 2.0 The definition of 'advance()' in that specification. | Recommendation |
Browser compatibility
BCD tables only load in the browser
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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