<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>登录</title>
<script>
</script>
<script>function fnLogin() {
var oUname=document.getElementById("uname")
var oUpass=document.getElementById("upass")
var oError=document.getElementById("error_box")
if(olname.value.length<6){
oError.innerHTML="用户名至少6 位"
}
}
}
</script>
</head>
<body>
<div class="box">
<h2>join</h2>
<div class="input-box">
用户名:<input id="uname" type="text" placeholder="用户名">
</div>
<div class="input-box">
密码:<input id="upass"type="password" placeholder="密码">
</div>
<div id="error-box"><br></div>
<div id="error_box"><br></div>
<div class="input_box">
<button onclick="fnLogin()">登陆</button>
</div>
</div>
</body>
</html>