console 命令行工具 X clear
console
<!DOCTYPE html>
<html>
<head>
    <script>
        function check(){
            var patten = /^[a-z|A-Z]{4}\d{2,6}$/;
            var qwer = document.getElementById("user").value;
            if(!patten.test(qwer)){
                alert("输入有误");
            }else{
                alert("输入正确");
            }
            return;
        }
    </script>
</head>
<body>
    <input type="test" id="user">
    <input type="button" value="查询" onclick="check()"/>
</body>
</html>