jQuery 插件

(1)required:true                必输字段
(2)remote:"check.php"      使用ajax方法调用check.php验证输入值
(3)email:true                    必须输入正确格式的电子邮件
(4)url:true                        必须输入正确格式的网址
(5)date:true                      必须输入正确格式的日期 日期校验ie6出错，慎用
(6)dateISO:true                必须输入正确格式的日期(ISO)，例如：2009-06-23，1998/01/22 只验证格式，不验证有效性
(7)number:true                 必须输入合法的数字(负数，小数)
(8)digits:true                    必须输入整数
(9)creditcard:                   必须输入合法的信用卡号
(10)equalTo:"#field"          输入值必须和#field相同
(11)accept:                       输入拥有合法后缀名的字符串（上传文件的后缀）
(12)maxlength:5               输入长度最多是5的字符串(汉字算一个字符)
(13)minlength:10              输入长度最小是10的字符串(汉字算一个字符)
(14)rangelength:[5,10]      输入长度必须介于 5 和 10 之间的字符串")(汉字算一个字符)
(15)range:[5,10]               输入值必须介于 5 和 10 之间
(16)max:5                        输入值不能大于5
(17)min:10                       输入值不能小于10

messages: {
    required: "This field is required.",
    remote: "Please fix this field.",
    email: "Please enter a valid email address.",
    url: "Please enter a valid URL.",
    date: "Please enter a valid date.",
    dateISO: "Please enter a valid date (ISO).",
    dateDE: "Bitte geben Sie ein gltiges Datum ein.",
    number: "Please enter a valid number.",
    numberDE: "Bitte geben Sie eine Nummer ein.",
    digits: "Please enter only digits",
    creditcard: "Please enter a valid credit card number.",
    equalTo: "Please enter the same value again.",
    accept: "Please enter a value with a valid extension.",
    maxlength: $.validator.format("Please enter no more than {0} characters."),
    minlength: $.validator.format("Please enter at least {0} characters."),
    rangelength: $.validator.format("Please enter a value between {0} and {1} characters long."),
    range: $.validator.format("Please enter a value between {0} and {1}."),
    max: $.validator.format("Please enter a value less than or equal to {0}."),
    min: $.validator.format("Please enter a value greater than or equal to {0}.")
},

jQuery.extend(jQuery.validator.messages, {
  required: "必选字段",
  remote: "请修正该字段",
  email: "请输入正确格式的电子邮件",
  url: "请输入合法的网址",
  date: "请输入合法的日期",
  dateISO: "请输入合法的日期 (ISO).",
  number: "请输入合法的数字",
  digits: "只能输入整数",
  creditcard: "请输入合法的信用卡号",
  equalTo: "请再次输入相同的值",
  accept: "请输入拥有合法后缀名的字符串",
  maxlength: jQuery.validator.format("请输入一个 长度最多是 {0} 的字符串"),
  minlength: jQuery.validator.format("请输入一个 长度最少是 {0} 的字符串"),
  rangelength: jQuery.validator.format("请输入 一个长度介于 {0} 和 {1} 之间的字符串"),
  range: jQuery.validator.format("请输入一个介于 {0} 和 {1} 之间的值"),
  max: jQuery.validator.format("请输入一个最大为{0} 的值"),
  min: jQuery.validator.format("请输入一个最小为{0} 的值")
});

<script src="../js/messages_cn.js" type="text/javascript"></script>

<script src="../js/jquery.js" type="text/javascript"></script>
<script src="../js/jquery.validate.js" type="text/javascript"></script>
<script src="./js/jquery.metadata.js" type="text/javascript"></script>

$().ready(function() {
 $("#signupForm").validate();
});


<form id="signupForm" method="get" action="">
    <p>
        <label for="firstname">Firstname</label>
        <input id="firstname" name="firstname" class="required" />
    </p>
 <p>
  <label for="email">E-Mail</label>
  <input id="email" name="email" class="required email" />
 </p>
 <p>
  <label for="password">Password</label>
  <input id="password" name="password" type="password" class="{required:true,minlength:5}" />
 </p>
 <p>
  <label for="confirm_password">确认密码</label>
  <input id="confirm_password" name="confirm_password" type="password" class="{required:true,minlength:5,equalTo:‘#password‘}" />
 </p>
    <p>
        <input class="submit" type="submit" value="Submit"/>
    </p>
</form>

$(document).ready(function() {
 $("#signupForm").validate({
        rules: {
   firstname: "required",
   email: {
    required: true,
    email: true
   },
   password: {
    required: true,
    minlength: 5
   },
   confirm_password: {
    required: true,
    minlength: 5,
    equalTo: "#password"
   }
  },
        messages: {
   firstname: "请输入姓名",
   email: {
    required: "请输入Email地址",
    email: "请输入正确的email地址"
   },
   password: {
    required: "请输入密码",
    minlength: jQuery.format("密码不能小于{0}个字 符")
   },
   confirm_password: {
    required: "请输入确认密码",
    minlength: "确认密码不能小于5个字符",
    equalTo: "两次输入密码不一致不一致"
   }
  }
    });
});

<form id="signupForm" method="get" action="">
    <p>
        <label for="firstname">Firstname</label>
        <input id="firstname" name="firstname" />
    </p>
 <p>
  <label for="email">E-Mail</label>
  <input id="email" name="email" />
 </p>
 <p>
  <label for="password">Password</label>
  <input id="password" name="password" type="password" />
 </p>
 <p>
  <label for="confirm_password">确认密码</label>
  <input id="confirm_password" name="confirm_password" type="password" />
 </p>
    <p>
        <input class="submit" type="submit" value="Submit"/>
    </p>
</form>

required:true 必须有值
required:"#aa:checked"表达式的值为真，则需要验证
required:function(){}返回为真，表时需要验证
后边两种常用于，表单中需要同时填或不填的元素