jQuery scrollTop()
Check scroll top value
<!DOCTYPE html> <html> <head> <script src="https://ajax.googleapis.com/ajax/libs/jquery/3.4.1/jquery.min.js"> </script>//from w w w . j av a2 s .com <script> $(document).ready(function() { $(window).scroll(function() { if ($(document).scrollTop() > 50) { $("p").addClass("test"); } else { $("p").removeClass("test"); } }); }); </script> <style> .test { background-color: yellow; } </style> </head> <body style="height:1550px;"> <p>Scroll down this page.</p> <p style="position:fixed;"> When you have scrolled 50 pixels from the top, add the class "test" (yellow background color) to the paragraph. Scroll up again to remove the class.</p> </body> </html>