The mode
read-only property of the IDBTransaction
interface returns the current mode for accessing the data in the object stores in the scope of the transaction (i.e. is the mode to be read-only, or do you want to write to the object stores?) The default value is readonly
.
Syntax
var myCurrentMode = IDBTransaction.mode;
Value
An IDBTransactionMode
object defining the mode for isolating access to data in the current object stores:
Value | Explanation |
---|---|
readonly |
Allows data to be read but not changed. |
readwrite |
Allows reading and writing of data in existing data stores to be changed. |
versionchange |
Allows any operation to be performed, including ones that delete and create object stores and indexes. This mode is for updating the version number of transactions that were started using IDBDatabase.setVersion() . Transactions of this mode cannot run concurrently with other transactions. Transactions in this mode are known as "upgrade transactions." |
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. At the end, we simply log the mode of the current transaction using mode
. 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. Duplicate items not allowed.</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.onsuccess) note.innerHTML += '<li>Request successful.</li>'; }; // Return the mode this transaction has been opened in (should be "readwrite" in this case) transaction.mode; };
Specification
Specification | Status | Comment |
---|---|---|
Indexed Database API 2.0 The definition of 'mode' in that specification. |
Recommendation | |
Indexed Database API Draft The definition of 'mode' in that specification. |
Recommendation |
Browser compatibility
Desktop | Mobile | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|
mode | Chrome
Full support
24
| Edge Full support 12 | Firefox
Full support
16
| IE Partial support 10 | Opera Full support 15 | Safari Full support 7 | WebView Android Full support Yes | Chrome Android Full support Yes | Firefox Android Full support 22 | Opera Android Full support 14 | Safari iOS Full support 8 | Samsung Internet Android Full support Yes |
Legend
- Full support
- Full support
- Partial support
- Partial support
- Requires a vendor prefix or different name for use.
- Requires a vendor prefix or different name for use.
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.)