Adds the classes 'selected' and 'highlight' to the matched elements. : addClass « jQuery « JavaScript Tutorial

<html>
  <head>
    <script type="text/javascript" src="js/jquery-1.3.2.js"></script>
    <script type="text/javascript">
        $(document).ready(function(){
               $("p:last").addClass("selected highlight");
        });
    </script>
    <style>
      .selected { color:red; }
      .highlight { background:yellow; }
    </style>    
  </head>
  <body>
    <body>
      <p>A</p>
      <p>B</p>
      <p>C</p>
    </body>
</html>

30.13.addClass
	30.13.1.	Add class to a selected Tag
	30.13.2.	Add style class to tag
	30.13.3.	Add two classes
	30.13.4.	addClass(class) adds the specified class(es) to each of the set of matched elements.
	30.13.5.	Adds the class 'selected' to the matched elements.
	30.13.6.	Adds the classes 'selected' and 'highlight' to the matched elements.