我正在尝试构建一个表单，在提交时发送包含填充数据的通知。当我运行代码时，它在控制台上显示此错误
polling-xhr.js:229 GET http://localhost:3000/socket.io/?EIO=4&transport=polling&t=NMtL4rR net::ERR_CONNECTION_REFUSED
这个错误看起来像是溢出
这是我的代码
管理.html
<!doctype html>
<html lang="en">
<head>
<!-- Required meta tags -->
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1, shrink-to-fit=no">
<!-- Bootstrap CSS -->
<link rel="stylesheet"
href="https://cdn.jsdelivr.net/npm/bootstrap@4.5.3/dist/css/bootstrap.min.css"
integrity="sha384-TX8t27EcRE3e/ihU7zmQxVncDAy5uIKz4rEkgIXeMed4M0jlfIDPvg6uqKI2xXr2"
crossorigin="anonymous">
<title>Hello, admin</title>
</head>
<body>
<div class="container" style="max-width: 500px;">
<div style="margin-top: 40px;"></div>
<h1>Send Notification</h1>
<form>
<div class="form-group">
<label for="name">name</label>
<input type="text" class="form-control" id="name" aria-describedby="emailHelp">
</div>
<div class="form-group">
<label for="profession">profession</label>
<input type="text" class="form-control" id="profession" aria-describedby="emailHelp">
</div>
<div class="form-group">
<label for="email">Email address</label>
<input type="email" class="form-control" id="email" aria-describedby="emailHelp">
</div>
<button …