jquery - How can I start moving elements when it reach the top of my window? -

i floating elements on scroll want start floating when reach top of window. has idea?

https://jsfiddle.net/eoopvgmc/13/

$(document).ready(function() {   $(document).on('scroll', function() {     $('.ads').css({       'top': $(window).scrolltop() + 'px'     });   }) }); 

you can use little piece of code:

$(document).ready(function() {     var offset = $('.ads').offset().top, top;     $(document).on('scroll', function() {         top = $(window).scrolltop() < offset ? '0' : $(window).scrolltop() - offset + 'px';         $('.ads').css({             'top': top         });     }); }); 

demo