Well, two solutions - one, put the initial class into the div element as i stated, and DONT run the code on load - it doesnt need to be run, the div already has the class it should have.
The other solution is to rewrite the function to be event-neutral, and instead target the select box by its selector (which you've already defined as '
select'), so instead of
event.target.value, it would be
event.target makes the code more flexible - if you wanted to put it onto multiple dropdowns on the same page, for example.