<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Demo</title>
</head>
<body>
<p>HELLO</p>
<script>
document.write(Date())
</script>
<button type="button" onclick=window.alert("用户名不得以数字开头")>LOGIM</button>
</body>
</html>
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Demo</title>
</head>
<body>
<p id="demo">HELLO</p>
<script>
document.getElementById("demo").innerHTML = Date();
</script>
<button type="button" onclick=window.alert("用户名不得以数字开头")>LOGIN</button>
</body>
</html>
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>登录</title>
<link rel="stylesheet" type="text/css" href="33.css">
<script>
function myLogin() {
var oUname = document.getElementById("umane");
var oError = document.getElementById("error_box");
var oUpass = document.getElementById("upass")
if(oUname.value.length<6){
oError.innerHTML="用户名至少为6位"
}
if(oUname.value.length>20){
oError.innerHTML="用户名不得超过20位"
}
if(oUname.value.length>6&oUname.value.length<20&oUpass.value.length<6){
oError.innerHTML="密码至少为6位"
}
if(oUname.value.length>6&oUname.value.length<20&oUpass.value.length>20){
oError.innerHTML="密码不得超过20位"
}
}
</script>
</head>
<body>
<div class="bigbox">
<div class="box">
<h2>登录</h2>
<div class="input_box">
账户：<input id="umane"type="text"placeholder="请输入用户名">
</div>
<div class="input_box">
密码：<input id="upass"type="password"placeholder="请输入密码">
</div>
<div id="error_box"><br></div>
<div class="input_box">
<button onclick="myLogin()">登录</button>
<button onclick=window.alert("是否取消登录？")>取消</button></div>
</div>
</div>
</body>
</html>
h2{
align:center;
}
.bigbox{
display: -webkit-flex;
display: flex;
width: 300px;
height: 250px;
padding-left: 100px;
padding-top: 50px;
background-color:cyan;
}
#input_box{
align:center;
margin:500px;
padding-left:500px;
}
#error_box{
color: hotpink;
}
body{ padding-right:500px; margin-top:100px; padding-left:500px; font-size:16px; padding-bottom:40px; padding-top:40px; font-family:verdana,Arial,Helvetica,sans-serif; }
