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    This article is in need of a technical review.

    The add() method of the IDBObjectStore interface returns an IDBRequest object, and, in a separate thread, creates a structured clone of the value, and stores the cloned value in the object store. This is for adding new records to an object store.

    To determine if the add operation has completed successfully, listen for the transaction’s complete event in addition to the IDBObjectStore.add request’s success event, because the transaction may still fail after the success event fires. In other words, the success event is only triggered when the transaction has been successfully queued.

    The add method is an insert only method. If a record already exists in the object store with the key parameter as its key, then an error ConstrainError event is fired on the returned request object. For updating existing records, you should use the IDBObjectStore.put method instead.


    var request = objectStore.add(myItem, optionalKey);


    An IDBRequest object on which subsequent events related to this operation are fired.


    This method may raise a DOMException with a DOMError of one of the following types:

    Exception Description
    ReadOnlyError The transaction associated with this operation is in read-only mode.
    TransactionInactiveError This IDBObjectStore's transaction is inactive.

    Any of the following conditions apply:

    • The object store uses in-line keys or has a key generator, and a key parameter was provided.
    • The object store uses out-of-line keys and has no key generator, and no key parameter was provided.
    • The object store uses in-line keys but no key generator, and the object store's key path does not yield a valid key.
    • The key parameter was provided but does not contain a valid key.
    InvalidStateError The IDBObjectStore has been deleted or removed.
    DataCloneError The data being stored could not be cloned by the internal structured cloning algorithm.


    In the following code snippet, we open a read/write transaction on our database and add some data to an object store using add(). 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. For a full working example, see our To-do Notifications app (view example live.)

    // Let us open our database
    var DBOpenRequest ="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
    function addData() {
      // Create a new object ready to insert 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>';


    The value to be stored.
    The key to use to identify the record. If unspecified, it results to null.


    Specification Status Comment
    Indexed Database API
    The definition of 'add()' in that specification.
    Candidate Recommendation  

    Browser compatibility

    Feature Chrome Firefox (Gecko) Internet Explorer Opera Safari (WebKit)
    Basic support 23webkit
    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: freaktechnik, fscholz, chrisdavidmills
    Last updated by: fscholz,