Help with generating access tokens in Node.js

I appreciate pointing it out. I have changed to the following after some searching,  and now works as intended

import * as https from "https";

const req = https.request("https://api.dropbox.com/oauth2/token",{
    method: "POST",
    headers:{
        "Authorization":`Basic ${Buffer.from(`${<APP_KEY>}:${<SECRET_KEY>}`).toString("base64")}`,
        "Content-Type":"application/x-www-form-urlencoded"
    }
}, (res) => {
    res.on("data", function(rawdat){
        console.log(rawdat.toString());
    })
});
req.write(new URLSearchParams({
    grant_type:"refresh_token",
    refresh_token: <REFRESH_TOKEN>
}).toString());
req.end();