一段简单的代码用来在网页上测试javascript程序

最近在看javascript，就写了一段简单的网页代码，方便自己看，如下图：

<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /> 
<script language="Javascript" type="text/javascript" >
    var num=14*2;
    {alert ("14*2="+num);
    }
</script>
</head>
<body>
</body>
</html>

再来一段：

<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /> 
<script language="Javascript" type="text/javascript" >
    var num1=5;
    var num2=10;
    var message="5+10="+(num1+num2);
    {alert (message);
    }
</script>
</head>
<body>
</body>
</html>