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("Heather1"+"<br/>");
        function callAlert(){
            alert("Welcome2");
        }
    </script>
    <button onclick="alert('welcome1')">点击1</button> 
    <button onclick="callAlert()">点击2</button>
</body>
</html>