How to get the Dropbox access token server-side (express.js) with https://github.com/dropbox/dropbox-js, inspired by https://gist.github.com/davidmerfield/9335c6f7506091ad606e

dropbox.js

app.get('/dropbox/auth', function(req, res) {
    var client = new Dropbox.Client({ key: "*********", secret: "*********"});

    client.authDriver({
      authType: function() {return "code";},
      url: function() {return "https://SERVER/dropbox/auth-callback";},
      doAuthorize: function(authUrl, stateParam, client, callback) {
        res.redirect(authUrl);// redirect to Dropbox
      },
      oauthQueryParams: ['access_token', 'expires_in', 'scope', 'token_type', 'code', 'error', 'error_description', 'error_uri', 'mac_key', 'mac_algorithm'].sort()
    });

    client.authenticate(function(error, client) {
      if (error) return console.log(error);
    });
  });
  
  app.get('/dropbox/auth-callback', function(req, res) {
    var code = req.query.code;

    var client = new Dropbox.Client({ key: "*********", secret: "*********"});
    client.authDriver({
      authType: function() {return "code";},
      url: function() {return "https://SERVER/dropbox/auth-callback";},
      doAuthorize: function(authUrl, stateParam, client, callback) {
        return callback({code: code});// this is the code from the callback
      },
      oauthQueryParams: ['access_token', 'expires_in', 'scope', 'token_type', 'code', 'error', 'error_description', 'error_uri', 'mac_key', 'mac_algorithm'].sort()
    });

    // this time, this will use the code to get the oauth token
    client.authenticate(function(error, client) {
      if (error) return console.log(error);
      
      console.log(client._oauth._token); // <-- TOKEN
      
      // store the token in a db, use it whenever needed
      // to get the user Dropbox id use client.getAccountInfo(function(error, accountInfo) {});
      
      return res.redirect('/');
    });

  });

That's really helpful, thanks a lot! Do you have an idea on how to use the token in upcoming (server-side) request? As the Documentation and a blog (https://blogs.dropbox.com/developers/2013/07/using-oauth-2-0-with-the-core-api/) says they expect a token Bearer to be send. My Idea was to store the token in a cookie and send it with every api call, but I cant't find a way using client.authenticate() or client.authDriver().