                        课程
                    
                        /前端开发
                        
                            /jQuery
                        
                        /jQuery插件——Validation Plugin

为什么没有效果呀，有没有大神有现在可以引用插件链接

<!DOCTYPE html>
<html>
<head>
   <meta charset="utf-8">
   <title></title>
   <style>
       fieldset{
           width: 400px;
           border:1px solid pink;
       }
   </style>
</head>
<body>
<script src="jq-cj/dist/jquery.validate.js"></script>
<script src="https://libs.baidu.com/jquery/1.9.1/jquery.js"></script>
<button id="yjh">点这</button>
<script>
$('#yjh').click(function(){
   alert("这个有用");
})
</script>

<script>
   $(document).ready(function(){//当页面载入后

       $('#demoForm').validate({//以下约定的是name值
           rules:{
               username:{
                   required:true,
                   minlength:2,
                   maxlength:10
               },
               password:{
                   required:true,
                   minlength:2,
                   maxlength:16
               }
           },
           messages:{//提示信息
               username:{
                   required:"必须填写用户名",
                   minlength:"用户名最小为2位",
                   maxlength:"最大为40位"
               },
               password:{
                   required:"必须填写密码",
                   minlength:"最小为2位",
                   maxlength:"最大为16位"
               }
           }
       });
   });

</script>
   <div>
       <form id="demoForm">
           <fieldset>
               <legend>用户登录</legend>
               <label for="username">用户名:</label>
               <input type="text" id="username" name="username"><br>

               <label for="password">密   码:</label>
               <input type="password" id="password" name="password"><br>

               <input type="submit" name="" value="登录">
               <input type="reset" name="" value="重置">
           </fieldset>
       </form>
   </div>
</body>
</html>