what has three legs and makes people want to cry? three-legged oauth. so heres a template written in node/express with login-with-twitter

oauth.node.js

const express = require('express');
const lwt = require("login-with-twitter");
const app = express()

// twitter oauth

const tw = new lwt({
  consumerKey: '[#yourkey]',
  consumerSecret: '[#yourkey]',
  callbackUrl: 'https://[#your url]/callback'
});

app.get("/callback", (req, res) => {
  res.send(`
  <script>
    location.href = location.href.replace("/c?", "/gen?") + "&token_secret=" + localStorage.tokenSecret;
  </script>
  `);
});

app.get("/generate-token", (req, res) => {
  tw.callback({
    oauth_token: req.query.oauth_token,
    oauth_verifier: req.query.oauth_verifier
  }, req.query.token_secret, (err, user) => {
    if (err) {
      throw err;
    }
    // auth tokens are stored in the user object. edit this part and add a logged in page
    res.send(`
    <script>
        location.href = "/logged-in?authdata=${escape(JSON.stringify(user))}"
    </script>
    `);
  });
});

app.get("/start-login", (req, res) => {
  tw.login((err, tokenSecret, url) => {
    if (err) {
      throw err;
    }
    res.send(`
    <script>
        localStorage.tokenSecret = "${tokenSecret}";
        location.href = "${url}";
    </script>
    `);
  });
});