SmoothScroll = function(element, options) {
	  options = options || {};

	  var $this = $(element);
	  var targetY = parseInt(options.position) || SmoothScroll.DEFAULTS.position;
	  var initialY = $this.scrollTop();
	  var lastY = initialY;
	  var delta = targetY - initialY;
	  // duration in ms, make it a bit shorter for short distances
	  // this is not scientific and you might want to adjust this for
	  // your preferences
	  var speed = options.speed ||
	      Math.min(750, Math.min(1500, Math.abs(initialY - targetY)));
	  // temp variables (t will be a position between 0 and 1, y is the calculated scrollTop)
	  var start;
	  var t;
	  var y;
	  var cancelScroll = function() {
	      abort();
	    };

	  // abort if already in progress or nothing to scroll
	  if (smoothScrollInProgress) {
	    return;
	  }

	  if (delta === 0) {
	    return;
	  }

	  // quint ease-in-out smoothing, from
	  // https://github.com/madrobby/scripty2/blob/master/src/effects/transitions/penner.js#L127-L136
	  function smooth(pos) {
	    if ((pos /= 0.5) < 1) {
	      return 0.5 * Math.pow(pos, 5);
	    }

	    return 0.5 * (Math.pow((pos - 2), 5) + 2);
	  }

	  function abort() {
	    $this.off('touchstart.smoothscroll.amui', cancelScroll);
	    smoothScrollInProgress = false;
	  }

	  // when there's a touch detected while scrolling is in progress, abort
	  // the scrolling (emulates native scrolling behavior)
	  $this.on('touchstart.smoothscroll.amui', cancelScroll);
	  smoothScrollInProgress = true;

	  // start rendering away! note the function given to frame
	  // is named "render" so we can reference it again further down
	  function render(now) {
	    if (!smoothScrollInProgress) {
	      return;
	    }
	    if (!start) {
	      start = now;
	    }

	    // calculate t, position of animation in [0..1]
	    t = Math.min(1, Math.max((now - start) / speed, 0));
	    // calculate the new scrollTop position (don't forget to smooth)
	    y = Math.round(initialY + delta * smooth(t));
	    // bracket scrollTop so we're never over-scrolling
	    if (delta > 0 && y > targetY) {
	      y = targetY;
	    }
	    if (delta < 0 && y < targetY) {
	      y = targetY;
	    }

	    // only actually set scrollTop if there was a change fromt he last frame
	    if (lastY != y) {
	      $this.scrollTop(y);
	    }

	    lastY = y;
	    // if we're not done yet, queue up an other frame to render,
	    // or clean up
	    if (y !== targetY) {
	      cAF(scrollRAF);
	      scrollRAF = rAF(render);
	    } else {
	      cAF(scrollRAF);
	      abort();
	    }
	  }

	  var scrollRAF = rAF(render);
	}
Smooth Scroll
@param position
@via http://mir.aculo.us/2014/01/19/scrolling-dom-elements-to-the-top-a-zepto-plugin/