Codekorrektur:
<html>
<head><title>Abstandsberechnung</title>
<script type="text/javascript">
var abstand = ???????;
function berechnen(){
alert('Abstand: '+abstand);
}
</script>
</head>
<body>
<br /><br /><br /><br /><br />
<a href="javascript:berechnen()"><img id="pic" name="pic" src="bild.jpg" /></a><br /><br
/>
</body>
</html>