index.js

/**
 * This is an example of a basic node.js script that performs
 * the Authorization Code oAuth2 flow to authenticate against
 * the Spotify Accounts.
 *
 * For more information, read
 * https://developer.spotify.com/web-api/authorization-guide/#authorization_code_flow
 */

var express = require('express'); // Express web server framework
var request = require('request'); // "Request" library
var cors = require('cors');
var querystring = require('querystring');
var cookieParser = require('cookie-parser');
// @ts-ignore
var config = require('./config-local.json');

var client_id = '2ebdb21ec087496d9f3cd88d45381e53'; // Your client id
var client_secret = '9744a5ab09d84c0e9da26a2d8f6f9c0b'; // Your secret
var redirect_uri = `${config.rootPath}/callback/`; // Your redirect uri

/**
 * Generates a random string containing numbers and letters
 * @param  {number} length The length of the string
 * @return {string} The generated string
 */
var generateRandomString = function(length) {
  var text = '';
  var possible =
    'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789';

  for (var i = 0; i < length; i++) {
    text += possible.charAt(Math.floor(Math.random() * possible.length));
  }
  return text;
};

var stateKey = 'spotify_auth_state';

var app = express();

app
  // .use(express.static(__dirname + '/public'))
  .use(express.static('./public'))
  .use(cors())
  .use(cookieParser());

app.get('/login', function(req, res) {
  var state = generateRandomString(16);
  res.cookie(stateKey, state);

  // your application requests authorization
  var scope = 'user-read-private user-read-email';
  res.redirect(
    'https://accounts.spotify.com/authorize?' +
      querystring.stringify({
        response_type: 'code',
        client_id: client_id,
        scope: scope,
        redirect_uri: redirect_uri,
        state: state
      })
  );
});

app.get('/callback', function(req, res) {
  // your application requests refresh and access tokens
  // after checking the state parameter

  var code = req.query.code || null;
  var state = req.query.state || null;
  var storedState = req.cookies ? req.cookies[stateKey] : null;

  if (state === null || state !== storedState) {
    res.redirect(
      '/#' +
        querystring.stringify({
          error: 'state_mismatch'
        })
    );
  } else {
    res.clearCookie(stateKey);
    var authOptions = {
      url: 'https://accounts.spotify.com/api/token',
      form: {
        code: code,
        redirect_uri: redirect_uri,
        grant_type: 'authorization_code'
      },
      headers: {
        Authorization:
          'Basic ' +
          new Buffer(client_id + ':' + client_secret).toString('base64')
      },
      json: true
    };

    request.post(authOptions, function(error, response, body) {
      if (!error && response.statusCode === 200) {
        var access_token = body.access_token,
          refresh_token = body.refresh_token;

        var options = {
          url: 'https://api.spotify.com/v1/me',
          headers: { Authorization: 'Bearer ' + access_token },
          json: true
        };

        // use the access token to access the Spotify Web API
        request.get(options, function(error, response, body) {
          console.log(body);
        });

        // ------------ huudungmg ------------
        res.redirect(`${config.rootPath}/#access_token=${access_token}`);
        // ------------ huudungmg ------------

        /* huudungmg takes comment        
        // we can also pass the token to the browser to make requests from there
        res.redirect(
          '/#' +
            querystring.stringify({
              access_token: access_token,
              refresh_token: refresh_token
            })
        );
        */
      } else {
        res.redirect(
          '/#' +
            querystring.stringify({
              error: 'invalid_token'
            })
        );
      }
    });
  }
});

app.get('/refresh_token', function(req, res) {
  // requesting access token from refresh token
  var refresh_token = req.query.refresh_token;
  var authOptions = {
    url: 'https://accounts.spotify.com/api/token',
    headers: {
      Authorization:
        'Basic ' +
        new Buffer(client_id + ':' + client_secret).toString('base64')
    },
    form: {
      grant_type: 'refresh_token',
      refresh_token: refresh_token
    },
    json: true
  };

  request.post(authOptions, function(error, response, body) {
    if (!error && response.statusCode === 200) {
      var access_token = body.access_token;
      res.send({
        access_token: access_token
      });
    }
  });
});

app.get('/', (req, res) => {
  // res.sendFile(__dirname + '/index.html');
  res.sendFile('./public/index.html');
});

const port = process.env.PORT || 8888;

app.listen(port, err => {
  if (err) console.log(err);
  console.log('Server started at port ' + port);
});