IDBRequest.source
  The source read-only property of the
  IDBRequest interface returns the source of the request, such as an
  Index or an object store. If no source exists (such as when calling
  indexedDB.open), it returns null.
Note: This feature is available in Web Workers
Value
  An object representing the source of the request, such as an IDBIndex,
  IDBObjectStore or IDBCursor.
Examples
  The following example requests a given record title, onsuccess gets the
  associated record from the IDBObjectStore (made available
  as objectStoreTitleRequest.result), updates
  one property of the record, and then puts the updated record back into the object
  store in another request. The source of the 2nd request is logged to the developer
  console. For a full working example, see our To-do
Notifications app (view
example live.)
var title = "Walk dog";
// Open up a transaction as usual
var objectStore = db.transaction(['toDoList'], "readwrite").objectStore('toDoList');
// Get the to-do list object that has this title as its title
var objectStoreTitleRequest = objectStore.get(title);
objectStoreTitleRequest.onsuccess = function() {
  // Grab the data object returned as the result
  var data = objectStoreTitleRequest.result;
  // Update the notified value in the object to "yes"
  data.notified = "yes";
  // Create another request that inserts the item
  // back into the database
  var updateTitleRequest = objectStore.put(data);
  // Log the source of this request
  console.log("The source of this request is " + updateTitleRequest.source);
  // When this new request succeeds, run the displayData()
  // function again to update the display
  updateTitleRequest.onsuccess = function() { displayData(); };
};
Specifications
| Specification | 
|---|
| Indexed Database API 3.0  # ref-for-dom-idbrequest-sourceā  | 
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.)