console 命令行工具 X clear

console

function fn()

{

    var a;

    document.write(a);

}

<!DOCTYPE html> 
<html>
<head>
    <meta charset="utf-8" />
    <title></title>
    <script>
        function callAlert(){
            alert('我被点了一下');
        }
    </script>
</head>
<body>
    <button onclick="alert('我被点击')">点我</button>
    <button onclick="callAlert()">点我一下</button>
    <script>
            //alert("Hi!")
    </script>
</body>
</html>