scrollTo

gistfile1.js

var scrollTo = function($target) {
  var $body = $('body,html');
  var currentOffset = $(window).scrollTop();
  var targetOffset = $target.offset().top;
  var distance = Math.abs(currentOffset - targetOffset);

  if (!$target.length) {
    return;
  }

  $body.animate({
    'scrollTop': $target.offset().top
  }, distance*0.5);
};