console 命令行工具 X clear
console
<!DOCTYPE html>
<html>
<head>
    <meta charset="utf-8"/>
    <title></title>
</head>
<body>
    <script type="text/javascript">
        document.write("Headther1"+"<br/>");
        function callAlert(){
            alert("Welcome2");
        }
        window.onload=function(){
            alert("hhhhhhhhhhhh！")
        }
        

    </script>
    <button onclick="alert("Welcome1")>点击1</button>
    <button onclick="callAlert()">点击2</button>
</body>
</html>