height(val): If no explicit unit was specified (like "em" or "%") then "px" is concatenated to the value. : height « jQuery « JavaScript Tutorial

<html>
  <head>
    <script type="text/javascript" src="js/jquery-1.3.2.js"></script>
    <script type="text/javascript">
        $(document).ready(function(){
        
               
                    $("div").one('click', function () {
                      $(this).height(30)
                             .css({cursor:"auto", backgroundColor:"green"});
                    });
               


        });
    </script>
<style>

  div { width:50px; height:70px; float:left; margin:5px;
        background:rgb(255,140,0); cursor:pointer; }
  
</style>
  </head>
  <body>
    <body>
          <div></div>
          <div></div>
                 
    </body>
</html>

30.48.height
	30.48.1.	Get document height
	30.48.2.	Get tag height
	30.48.3.	Set height to
	30.48.4.	Window height
	30.48.5.	height(): find the height of the window and document.
	30.48.6.	height(val): If no explicit unit was specified (like "em" or "%") then "px" is concatenated to the value.