Open a write transaction with the :js-sdk:`Realm.write() <classes/Realm-1.html#write>` method.
Instantiate an unmanaged object instance of your JavaScript class or a class that extends :js-sdk:`Realm.object <classes/Realm.Object.html>`. For more information, refer to :ref:`sdks-object-models`.
Pass the unmanaged object instance to the :js-sdk:`Realm.create() <classes/Realm-1.html#create>` method to persist the object data to the database. You can assign the new managed object to a variable or return it from the write transaction block to observe or work with it immediately.
Note that asymmetric objects are write-only. Once an asymmetric object is synced, it is deleted from the device database. You cannot read, update, or delete an asymmetric object from the device.