<form method="post" >
 <!-- token验证 -->
 <!--{{ csrf_field() }}-->
 <div class="form-group" style="width:30%">
  <label for="exampleInputPassword1">昵称</label>
  <input type="name" id="nickname" name="nickname" class="form-control" id="exampleInputname1" placeholder="用于评论昵称">
 </div>
 <div class="form-group">
  <label for="exampleInputEmail1">Email </label>
  <input style="width:30%" type="email" id="email" name="email" class="form-control" id="exampleInputEmail1" placeholder="用于接收回复消息通知">
  <span id="error_massage"></span>
 </div>
 <div class="form-group" style="width:60%;">
  <label for="name">留言内容</label>
  <textarea class="form-control" id="content" name="text" rows="3" placeholder="评论内容"></textarea>
  </div>
  <button type="submit" class="btn btn-default">Submit</button>
 </form>

 public function postMassage(Request $Request)
 {  
   $email  = $Request->email;
   $messages = $this->article_messages->where('email',$email)->first();
   if (!empty($messages)) {
   return response()->json(['status' => 'ok','code' => 400,'message' => '该邮箱已存在！换一个吧！',]);
   }
 }

<script type="text/javascript">
  $("form").submit(function(e){
    e.preventDefault();//阻止默认提交,表单不写method="post"这个可以不要
    console.log(11);
    var nickname = $('#nickname').val();
    var email = $('#email').val();
    var content = $('#content').val();
    $.ajax({
     type: "post",
     url: "/article/message",
     dataType:"json",
     data:{
     "nickname":nickname,
     "email":email,
     "content":content,
     "_token":"{{ csrf_token() }}",
     },
     success: function(data) {
      if (data.code == 400) {
       console.log(data);
       document.getElementById('error_massage').innerHTML =data.message;
      } else {

      }
     }
    });
    // $.post("/article/message", {
    //    "nickname":nickname,
    //     "email":email,
    //     "content":content,
    //     "_token":"{{ csrf_token() }}",
    // },
    // function(data){
    //  console.log(data);
    // });
   })

  </script>