'http://127.0.0.1:5500' has been blocked by CORS policy-CodePudding

this is index.html code
<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Secret</title>
    <script defer src="http://localhost:8000/socket.io/socket.io.js"></script>
    <script defer src="./client/client.js"></script>
    <link rel="stylesheet" href="./css/index.css">
</head>
<body>
    <div class="main">
        <div class="head">this is a chat app</div>
        <div class="container">
            <div class="message right">Lorem ipsum dolor sit qui.</div>
            <div class="message left">Lorem ipsum dolor sit, amet consectetur adipisicin</div>
        </div>
        <div class="send">
            <form action="#" id="send_msg">
                <input type="text" name="messageInput" placeholder="type message