Hi there Yizuhi,
Hope you're doing well.
About your first question, the correct syntax is to include parenthesis. I always included them and never had problems :)
About your scenario, what is happening is since the second expression of the assign expects a function reference, you need to provide one. With your code, you are immediately calling the function and passing its result. That's why it triggers the function automatically and causes you problems afterwards. This should be the correct syntax:
object.onclick = function(){myScript};
So you should do something like this:
Element.onclick = function(){
$actions.OnElementClicked();
};
I just did some tests and it is working like a charm :)

Hope that this helps you!
Kind regards,
Rui Barradas