How to update a item in a object store in Index db

I am able get Item by id. But how to update the item ?
 

using the following code i am getting value

var transaction = db.transaction("Emp", IDBTransaction.READ_WRITE);
                var objectStore = transaction.objectStore("Emp");
 
                var request = objectStore.get(id);                
                request.onsuccess = function(evt) {  
                //alert(request.result.Name);
                if(request.result)
                {                
                $('#txt_1').val(request.result.Name);
                $('#txt_2').val(request.result.Cname);
                 $('#txt_3').val(request.result.Salary);
                 $('#txt_4').val(request.result.Address);
}
}

 
if i want to change Salary of that particular record. how to do it