Scrolls the window to the required position (Please note that this snippet works best with top scrolling just for now)

scroll-window-to.js

/*
* Scrolls the window to the required position using animation with custom easing.
* The required position can be set with the 1st argument ('position');
* The fineness of the animation can be customized by using the 'speed' (2nd) argument, which ranges between 0.1 (very fine) and 1 (instant jump).
* Usage #1:
* scrollWindowTo(0, 0.2); // -> Scrolls the page to the top with a fine animation 
* Usage #2:
* scrollWindowTo(100, 1); // -> Makes the page jump to 100px
*/
var scrollWindowTo = (function(){
  var timer = 0, posTo = 0, scrollingSpeed = 0.1;
  
  // Returns the current scroll position
  function scrollPosition() {
    if (typeof pageYOffset != "undefined") {
      return pageYOffset;
    } else {
      var body = document.body, doc = document.documentElement;
      doc = doc.clientHeight ? doc: body;
      return doc.scrollTop;
    }
  };
  
  // Calculates the next scroll position with a custom easing equation
  function easeScrolling() {
    if(Math.round(Math.abs(currentPos - posTo)) > 0) {
      currentPos += (posTo - currentPos) * scrollingSpeed;
    } else {
      currentPos = posTo;
      window.clearInterval(timer);
    }
    window.scrollTo(0, currentPos);
  };
  
  /*
  * Starts the scrolling to the 'position' which can be anything between 0 and the page height
  * @param position The required position to scroll the window to
  * @param speed The speed can range from 0 to 1 and sets the speed of the animation
  */
  return function (position, speed) {
    if (timer > 0) {
      window.clearInterval(timer);
    }
    posTo = typeof position === "number" ? Math.abs(position) : 0;
    scrollingSpeed = typeof speed === "number" && speed >= 0.1 ? speed : scrollingSpeed;
    currentPos = scrollPosition();
    timer = window.setInterval(easeScrolling, 16.7);
  };
}());