Opacity scroll effect

scroll.js

  // http://stackoverflow.com/a/8702428

  var fadeStart=100, // 100px scroll or less will equiv to 1 opacity
    fadeUntil=800, // 200px scroll or more will equiv to 0 opacity
    fading = $('.slider-inner-container-fader');
  
  $(window).bind('scroll', function(){
    var offset = $(document).scrollTop(),
      opacity=0;
    if( offset<=fadeStart ){
      opacity=1;
    } else if ( offset<=fadeUntil ){
      opacity=1-offset/fadeUntil;
    }
    fading.css('opacity',opacity);
  });