The System.TriggerOperation enum has the following values:

• BEFORE_INSERE
• AFTER_INSERT
• BEFORE_UPDATE
• AFTER_UPDATE
• BEFORE_DELETE
• AFTER_DELETE
• AFTER_UNDELETE

The new Trigger context variable Trigger.operationType will return System.TriggerOperation enum during trigger context.

If you combine this new context variable and the new Apex switch feature, trigger code becomes much easy to implement and understand.

Sample Switch and enum in Triggers:

trigger AccountTrigger on Account(before insert, after insert, before update, after update, before delete, after delete, after undelete) {
    
    switch on Trigger.operationType {
        
        when BEFORE_INSERT {
            //Invoke before insert trigger handler
            system.debug('Before Insert');
        }
        when AFTER_INSERT {
            //Invoke after insert trigger handler
            system.debug('After Insert');
        }
        when BEFORE_UPDATE {
            //Invoke before update trigger handler
            system.debug('Before Update');
        }
        when AFTER_UPDATE {
            //Invoke after update trigger handler
            system.debug('After Update');
        }
        when BEFORE_DELETE {
            //Invoke before delete trigger handler
            system.debug('Before Delete');
        }
        when AFTER_DELETE {
            //Invoke after delete trigger handler
            system.debug('After Delete');
        }
        when AFTER_UNDELETE {
            //Invoke after undelete trigger handler
            system.debug('After Undelete');
        }
    }
}