ScrollMagic ♥ Demo
▻http://scrollmagic.io
ScrollMagic helps you to easily react to the user’s current scroll position.
It’s the perfect library for you, if you want to ...
animate based on scroll position – either trigger an animation or synchronize it to the scrollbar movement (like a playback scrub control).
pin an element starting at a specific scroll position – either indefinitely or for a limited amount of scroll progress (sticky elements).
toggle CSS classes of elements on and off based on scroll position.
effortlessly add parallax effects to your website.
create an infinitely scrolling page (ajax load of additional content).
add callbacks at specific scroll positions or while scrolling past a specific section, passing a progress parameter.