add class to random element
setRandomClass(); setInterval(function () { setRandomClass(); }, 2000);//number of milliseconds (2000 = 2 seconds) function setRandomClass() { var ul = $("ul"); var items = ul.find("li"); var number = items.length; var random = Math.floor((Math.random() * number)); items.removeClass("special"); items.eq(random).addClass("special"); }