JQuery登陆验证

<script type="text/javascript" src="js/jquery-1.8.3.js"></script><script type="text/javascript">$(function(){// 为看不清楚绑定事件$("#see").click(function(){$("#vimg").attr("src", "${ctx}/verify.action?random=" + Math.random());});// 为验证码绑定click与mouseover$("#vimg").mouseover(function(){$(this).css("cursor", "pointer");}).click(function(){$("#see").trigger("click");});// 登录验证$("#loginBtn").click(function(){// 做表单输入校验var userId = $("#userId");var password = $("#password");var code = $("#code");var msg = "";if ($.trim(userId.val()) == ""){msg = "用户名不能为空！";userId.focus();}else if (!/^\w{5,20}$/.test($.trim(userId.val()))){msg = "用户名格式不正确！";userId.focus();}else if ($.trim(password.val()) == ""){msg = "密码不能为空！";password.focus();}else if (!/^\w{6,20}$/.test($.trim(password.val()))){msg = "密码格式不正确！";password.focus();}else if ($.trim(code.val()) == ""){msg = "验证码不能为空！";code.focus();}else if (!/^[0-9a-zA-Z]{4}$/.test($.trim(code.val()))){msg = "验证码格式不正确！";code.focus();}if (msg != ""){alert(msg);}else{// 获取表单中的参数var params = $("#loginForm").serialize();//alert(params);// 发送登录的异步请求$.post("${ctx}/loginAjax.action", params, function(data, status){alert(data.tip);}, "json");}});// 为document绑定onkeydown事件监听是否按了回车键$(document).keydown(function(event){if (event.keyCode === 13){ // 按了回车键$("#loginBtn").trigger("click");}});});</script><form  method="post" id="loginForm" >用户名:<input type="text" id="userId" value="" size="20" ></div>

密　码:<input type="password" id="password">  验证码:<input type="text" style="margin-left:5px;width:35px;" id="code" maxlength="4"/><img title="验证码" width="55" height="22" id="vimg" src="${ctx}/verify.action"><a href="javascript:void(0)" id="see">看不清楚</a></td>