$(window).scroll(function() {
var scroll = $(window).scrollTop();
if (scroll >= 500) {
$(".clearHeader").addClass("darkHeader");
}
}); $('some_element').addClass('some-class');
// You can add more than one class at one time
$('some_element').addClass('some-class another-class yet-another-class');
// Even thought jQuery allows you to do this
$('some_element').addClass('some-class').addClass('another-class').addClass('yet-another-class');
// That would be really wasteful, think of the planet!
// But more importantly, your RAM
// oh and those poor folks who be viewing your website