I don't know if it exist but, it will awesome if when you exit some trigger that execute once a function, like onExit.

Usage:
onExit: function(other){
  other.doSomething();
}

Now I'm using a fix, setting in entity each frame to know if is colliding.
In my case the player can use a special attack only colliding with the trigger, but I don't know when the player leave the trigger. =/