fires before updating a record (records)
| id | string|number | the item's id | 
| state | string | the item's state (operation type) | 
| data | object | data that will be sent to the server side | 
dp.attachEvent("onBeforeUpdate", function(id, state, data){
    //your code here
    return true;
});
The event fires for each updating record and before onBeforeDataSending.
The event can be blocked. Returning false from event handler will prevent data sending.
Possible response statuses are the following: