Unconditional Delivery Listeners

The where clause argument in the addDeleteListener method is optional. When it is not provided, the real-time database will deliver any object  which is being deleted from the database's table:

Using Untyped Objects

const orderEventHandler = Backendless.Data.of( 'Order' ).rt();

const onObjectDeleted = object => 
                       console.log( 'an Order object has been deleted. Object Id - ', object.objectId );

const onError = error => 
                console.log( 'Server reported an error', error );

orderEventHandler.addDeleteListener( onObjectDeleted, onError );

Custom Class/Function

function Order() {
  this.objectId = undefined;
  this.orderAmount = 0;
}

const orderEventHandler = Backendless.Data.of( Order ).rt();

const onObjectDeleted = object => 
                       console.log( 'an Order object has been deleted. Object Id - ', object.objectId );

const onError = error => 
                console.log( 'Server reported an error', error );

orderEventHandler.addDeleteListener( onObjectDeleted, onError );