Adding to Peter Leow's solution, you should also use
event.preventDefault()
$(document).ready(function() {
$('.footer-top').click(function(event){
event.preventDefault();
$('html,body').animate({ scrollTop: 0 }, 'slow');
});
});
You should use this because the link has a href of #, which will make the browser leap to the top of the page without animation.
event.preventDefault()
cancelles the default behaviour.