Drupal 7 scrollTop Link

html

<a href="#" id="to-top" title="Back to top">To top</a>

js

Drupal.behaviors.totop = {
  attach: function (context, settings) {
    $('#to-top:not(.totop-processed)', context).addClass('totop-processed').each(function() {	
      $(this).click(function(){
        $('html, body').animate({scrollTop:0}, 'slow');
        return false;
      })
    });
  }
};