Altro metodo....
codice:
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<title>Untitled</title>
</head>
<body>
<script language="JavaScript" type="text/javascript">
<!--
oraI = 14.45;
oraF = 17.00;
//
minI = (oraI - parseInt(oraI))*100;
minF = (oraF - parseInt(oraF))*100;
i = parseInt(oraI) * 60 + minI;
f = parseInt(oraF) * 60 + minF;
diff = f - i;
diff = Math.round(diff,0);
ore = parseInt(diff / 60);
min = Math.round((diff / 60 - ore)*60);
alert(ore + " ore - " + min + " minuti");
//-->
</script>
</body>
</html>