.js

app.get('/auth/callback', function(req,res){
  var optAuthorize = {
    url: config.url_oauth,
    method: 'POST',
    form: {
      grant_type: 'authorization_code',
      code: req.query.code,
      client_id: config.client_id,
      client_secret: config.client_secret
    }
  };  
  request(optAuthorize, function(error, res, body) {
    // làm thế nào để send body ra browser 
  });
});