salve a tutti,

ho questa pagina. all'evento onclick dei link eseguo la funzione prova:
codice:
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"
"http://www.w3.org/TR/html4/loose.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
	<head>
		<style type="text/css">
			a#p{
				font-family:Verdana, Arial, Helvetica, sans-serif;
				font-weight:bold;
				font-size:15px;
				color:#666666;
				text-decoration:none;
				filter:alpha(opacity=30);
				-moz-opacity: 0.3;
			}
			a#p:hover{
				font-family:Verdana, Arial, Helvetica, sans-serif;
				font-weight:bold;
				font-size:17px;
				color:#F95147;
				text-decoration:none;
				filter:alpha(opacity=75);
				-moz-opacity: 0.75;
			}
			#current{
				font-family:Verdana, Arial, Helvetica, sans-serif;
				font-weight:bold;
				font-size:15px;
				color:#0099FF;
				text-decoration:none;
			}
		</style>
		<script type="text/javascript">
			function prova(){
				var current = document.getElementById("current");
				var appName = navigator.appName;
				if (appName== "Netscape") {
					event.target.id = "current";
				} else {
					event.srcElement.id = "current";
				}
				if (current != null) {current.id = "p";}
			}
		</script>
		<title>Documento senza titolo</title>
		<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1" />
	</head>
	<body>
	    <div>
		    1
		    2
		    3
		</div>
	</body>
</html>
ma quando faccio click sul link firefox si incazza e mi dice: "event is not defined"
dove sbaglio?

grazie