将校验规则写到控件中
<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>
Tips：
使用class="{}"的方式，必须引入包：jquery.metadata.js
可以使用如下的方法，修改提示内容：
class="{required:true,minlength:5,messages:{required:'请输入内容'}}"
在使用equalTo关键字时，后面的内容必须加上引号，如下代码：
class="{required:true,minlength:5,equalTo:'#password'}"