CODE EXAMPLE FOR JAVASCRIPT

jquery on scroll x pixels

$(document).scroll(function() {
               var value=$(document).scrollTop();

                if ( value >= 1000 ) { /*do this*/; return;}
                if ( value >= 500 ) { /*do this*/; return;}
                if ( value >= 150 ) { /*do this*/; return;}
                if ( value >= 30 ) { /*do this*/; return;}
                /* else */
                /*do this*/
            });