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    IDBTransaction.mode

    This article is in need of a technical review.

    The mode 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 = transaction.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.
     

    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 our new item going into the database
        note.innerHTML += '<li>New item added to database.</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
    The definition of 'mode' in that specification.
    Candidate Recommendation  

    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
    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 Not supported

    See also

    Document Tags and Contributors

    Contributors to this page: fscholz, chrisdavidmills
    Last updated by: fscholz,