Adds the specified class to each of the set of matched elements with an optional transition between the states.
$("p").click(function () { $(this).addClass("selected", 1000); });
<!DOCTYPE html> <html> <head> <link type="text/css" href="http://jqueryui.com/latest/themes/base/ui.all.css" rel="stylesheet" /> <script type="text/javascript" src="http://jqueryui.com/latest/jquery-1.3.2.js"></script> <script src="http://ui.jquery.com/latest/ui/effects.core.js"></script> <style type="text/css"> p { cursor: pointer; font-size: 1.2em; } .selected { color:red; } </style> <script type="text/javascript"> $(document).ready(function(){ $("p").click(function () { $(this).addClass("selected", 1000); }); }); </script> </head> <body style="font-size:62.5%;"> <p>Click me to add a 'selected' class.</p> <p>Click me to add a 'selected' class.</p> <p>Click me to add a 'selected' class.</p> </body> </html>