Example

In the following code snippet, we open a transaction and manipulate an entire data set using a cursor. Because the specification is still evolving, Chrome uses prefixes in the methods. Chrome uses the webkit prefix. For example, instead of just IDBCursor.NEXT, use webkitIDBCursor.NEXT. Firefox does not use prefixes, except in the opening method (mozIndexedDB). Event handlers are registered for responding to various situations.

// Taking care of the browser-specific prefixes.
window.indexedDB = window.indexedDB || window.mozIndexedDB || window.webkitIndexedDB;
window.IDBTransaction = window.IDBTransaction || window.webkitIDBTransaction;
window.IDBKeyRange = window.IDBKeyRange || window.webkitIDBKeyRange;
window.IDBCursor = window.IDBCursor || window.webkitIDBCursor;
var db;

...

function cursorTest() {
  // Start a transaction on an object store called "my-store-name"
  // By default, transactions are opened with read-only access.
  // If you want to have write access, see IDBDatabase.
  var trans = db.transaction('my-store-name');
  // Get a reference to the object store.
  var store = trans.objectStore('my-store-name');
  // Create a cursor with two optional parameters.  
  // The first parameter sets the cursor over a specified key range;
  // while the second one sets the direction of the cursor.  
  // In this case, the direction is set to IDBCursor.PREV,  
  // which lets you start at the upper bound of the key range
  // and then moves downwards. 
  // If you don't want duplicates included, use PREV_NO_DUPLICATE instead.
  var curreq = store.openCursor(IDBKeyRange.bound(1, 4), IDBCursor.PREV); 
  // The "onsuccess" event fires when the cursor is created and 
  // every time the cursor iterates over data. 
  // The following block of code runs multiple times,
  // until the cursor runs out of data to iterate over.
  // At that point, the result's request becomes null.
  curreq.onsuccess = function (e) {
    var cursor = curreq.result;
    // If the cursor is pointing at something, ask for the data.    
    if (cursor) {
      var getreq = store.get(cursor.key);
      // After the data has been retrieved, show it.
      getreq.onsuccess = function (e) {
        console.log('key:', cursor.key, 'value:', getreq.result);
        // OK, now move the cursor to the next item. 
        cursor.continue();
      };
    }
  };
};

To learn more about various topics, see the following

• Starting transactions - IDBDatabase
• Setting transaction modes - IDBTransaction
• Setting a range of keys - IDBKeyRange
• Creating cursors - IDBIndex

update()

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.

IDBRequest update (
  in any value
) raises (IDBDatabaseException, DOMException);

advance()

Sets the number times a cursor should move its position forward.

IDBRequest advance (
  in long count
) raises (IDBDatabaseException);

continue()

Advances the cursor to the next position along its direction, to the item whose key matches the optional key parameter. If no key is specified, advance to the immediate next position, based on the cursor's direction.

void continue (
  in optional any key
) raises (IDBDatabaseException);

delete()

Returns an IDBRequest object, and, in a separate thread, deletes the record at the cursor's position, without changing the cursor's position. Once the record is deleted, the cursor's value is set to null.

IDBRequest delete (
) raises (IDBDatabaseException);