...scrollTop($(this)...)

I have a few divs with the .class class whose scroll position is defined by another child of its parent, so I need to assign a scrollTop() with $(this), something like

$(".class").scrollTop($(this).parent().find('.child').scrollTop()); 

But that code doesn't work...

$(".class").scrollTop(
    function(){
        $(this).parent().find('.child').scrollTop()
    }
);

Doesn't work either. Any clue?