Passing The String-name Of The Function To AddEvent

I would like to separate my javascript completely from my xhtml. in the
end there should be only

<script type="text/javascript" src="javalib.js"></script>
in the head-tag to my javascript.

Because I want to use some ajax-requests and other javascript-functions
on my xhtml, I need to dynamically add event handlers to any possible
dom-elements. All solutions I found so fare are for specific, pre-known
dom-elements: like 'all <imgof a certain <span>-class get an
onmouseover event handler'. But I need a function, which runs onload of
the window and dynamically determines, which dom-elments need an event
handler and which ones don't. Code: