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 behaviour 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. Since such catastrophic events are rare most consumers should not need to concern themselves further.
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() { ... };
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 our new item going into the database note.innerHTML += '<li>New item added to database.</li>'; }; };
Specification
Specification | Status | Comment |
---|---|---|
Indexed Database API The definition of 'oncomplete' in that specification. |
Editor's Draft |
Browser compatibility
Feature | Chrome | Firefox (Gecko) | Internet Explorer | Opera | Safari (WebKit) |
---|---|---|---|---|---|
Basic support | 23webkit 24 |
10 moz 16.0 (16.0) |
10, partial | 15 | 7.1 |
Available in workers | (Yes) | 37.0 (37.0) | ? | (Yes) | ? |
Feature | Android | Firefox Mobile (Gecko) | Firefox OS | IE Phone | Opera Mobile | Safari Mobile |
---|---|---|---|---|---|---|
Basic support | 4.4 | 22.0 (22.0) | 1.0.1 | 10 | 22 | 8 |
Available in workers | (Yes) | 37.0 (37.0) | (Yes) | ? | (Yes) | ? |
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.)
License
© 2016 Mozilla Contributors
Licensed under the Creative Commons Attribution-ShareAlike License v2.5 or later.
https://developer.mozilla.org/en-us/docs/web/api/idbtransaction/oncomplete