IDBTransaction.oncomplete
The oncomplete
event handler of the
IDBTransaction
interface handles the complete event, fired when the
transaction successfully completes.
As of Firefox 40, IndexedDB transactions have relaxed durability guarantees to increase
performance (see bug 1112702), which is the same behavior as other
IndexedDB-supporting browsers. Previously in a readwrite
transaction
IDBTransaction.oncomplete
was fired only when all data was guaranteed to
have been flushed to disk. In Firefox 40+ the complete
event is fired after
the OS has been told to write the data but potentially before that data has actually
been flushed to disk. The complete
event may thus be delivered quicker than
before, however, there exists a small chance that the entire transaction will be lost if
the OS crashes or there is a loss of system power before the data is flushed to disk.
Note:
This feature is available in Web Workers.Note: In Firefox, if you wish to ensure durability for some reason
(e.g. you're storing critical data that cannot be recomputed later) you can force a
transaction to flush to disk before delivering the complete
event by
creating a transaction using the experimental (non-standard)
readwriteflush
mode (see IDBDatabase.transaction
.) This is
currently experimental, and can only be used if the
dom.indexedDB.experimental
pref is set to true
in
about:config
.
Syntax
transaction.oncomplete = function(event) { ... };
Example
In the following code snippet, we open a read/write transaction on our database and add
some data to an object store. Note also the functions attached to transaction event
handlers to report on the outcome of the transaction opening in the event of success or
failure. Note the transaction.oncomplete = function(event) { };
block,
which reports back when the transaction was successful. For a full working example, see
our To-do Notifications app
(view example live.)
// Let us open our database
var DBOpenRequest = window.indexedDB.open("toDoList", 4);
DBOpenRequest.onsuccess = function(event) {
note.innerHTML += '<li>Database initialised.</li>';
// store the result of opening the database in the db variable.
// This is used a lot below
db = DBOpenRequest.result;
// Run the addData() function to add the data to the database
addData();
};
function addData() {
// Create a new object ready for being inserted into the IDB
var newItem = [ { taskTitle: "Walk dog", hours: 19, minutes: 30, day: 24, month: "December", year: 2013, notified: "no" } ];
// open a read/write db transaction, ready for adding the data
var transaction = db.transaction(["toDoList"], "readwrite");
// report on the success of opening the transaction
transaction.oncomplete = function(event) {
note.innerHTML += '<li>Transaction completed: database modification finished.</li>';
};
transaction.onerror = function(event) {
note.innerHTML += '<li>Transaction not opened due to error: ' + transaction.error + '</li>';
};
// create an object store on the transaction
var objectStore = transaction.objectStore("toDoList");
// add our newItem object to the object store
var objectStoreRequest = objectStore.add(newItem[0]);
objectStoreRequest.onsuccess = function(event) {
// report the success of the request (this does not mean the item
// has been stored successfully in the DB - for that you need transaction.oncomplete)
note.innerHTML += '<li>Request successful.</li>';
};
};
Specifications
Specification | Status | Comment |
---|---|---|
Indexed Database API 2.0 The definition of 'oncomplete' in that specification. |
Recommendation | |
Indexed Database API 2.0 The definition of 'oncomplete' 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.)
-
complete
event