I am creating OAuth2 for my application by which the people who are redirected to the server by clickking it will get the verified role. Can somebody please help me on how i can add it in my script. Right now I am using the script given below:

const express = require('express');
const { port } = require('./config.json');

const app = express();

app.get('/', (request, response) => {
    console.log(`The access code is: ${request.query.code}`)

;
    return response.sendFile('index.html', { root: '.' });
});

app.listen(port, () => console.log(`App listening at http://localhost:${port}`));

and from the index file they get redirected to the server here's the index.html script:

<script>

  window.location.href = "https://discord.gg/DhsYQ3u4jj";

</script>
<div id="info">Congrats! You have been successfully connected to Discord.</div>
<a id="login" style="display: none;" href="https://discord.gg/jkBJarBY">Click here to Join Akudo's official Discord!</a>
<script>
    window.onload = () => {
        const fragment = new URLSearchParams(window.location.hash.slice(1));
        const [accessToken, tokenType] = [fragment.get('access_token'), fragment.get('token_type')];

        if (!accessToken) {
            return (document.getElementById('login').style.display = 'block');
        }

        fetch('https://discord.com/api/users/@me', {
            headers: {
                authorization: `${tokenType} ${accessToken}`,
            },
        })
            .then(result => result.json())
            .then(response => {
                const { username, discriminator } = response;
                document.getElementById('info').innerText += ` ${username}#${discriminator}`;
            })
            .catch(console.error);
    };

</script>