<head runat="server">
<title></title>
<script type="text/javascript" language="JavaScript">
function checkform() {
if (document.getElementById('usrname').value == "") {
window.alert("请输入您的用户名！");
document.Log.usrname.focus();
return false;
}
var patrn = /^[a-zA-Z0-9 ]{5,20}$/;
if (!patrn.exec(document.getElementById('usrname').value)) {
window.alert("用户名只能由字母或者数字组成，并且不能少于5个字符，不能大于20个字符！");
document.getElementById('usrname').focus();
return false
}
if (document.getElementById('passwd').value == "") {
window.alert("请输入您的密码！");
document.getElementById('passwd').focus();
return false;
}
if ((document.getElementById('passwd').value.length < 6) || (document.getElementById('passwd').value.length > 20)) {
window.alert("登录密码不能少于6个字符，不能多于20个字符！");
document.getElementById('passwd').focus();
return false;
}
Log.submit.disabled = true;
return true;
}
</script>
</head>
方法一： HTML控件
<body>
<form id="form1" runat="server">
<div>
<input id="usrname" type="text"/>
<input id="passwd" type="password" />
<input id="Button1" type="button" value="提交" onclick="checkform()"/>
</div>
</form>
</body>
方法二：服务器控件
<body>
<form id="form1" runat="server">
<div>
<asp:TextBox ID="usrname" runat="server"></asp:TextBox>
<asp:TextBox ID="passwd" runat="server"></asp:TextBox>
<asp:Button ID="Button2" runat="server" Text="Button" OnClientClick="checkform()"/>
</div>
</form>
</body>