app.js

const http = require('http');
const port=process.env.PORT || 3000
const server = http.createServer((req, res) => {
res.statusCode = 200;
res.setHeader('Content-Type', 'text/html');
res.end('<h1>Hello World</h1>');
});
server.listen(port,() => {
console.log(`Server running at port `+port);
});


var Twit = require('twit')

var fs = require('fs'),
    path = require('path'),
    Twit = require('twit'),
    config = require(path.join(__dirname, 'config.js'));

var T = new Twit(config);

function random_from_array(images){
  return images[Math.floor(Math.random() * images.length)];
}

function upload_random_image(images){
  console.log('Opening an image...');
  var image_path = path.join(__dirname, '/images/' + random_from_array(images)),
      b64content = fs.readFileSync(image_path, { encoding: 'base64' });

  console.log('Uploading an image...');

  T.post('media/upload', { media_data: b64content }, function (err, data, response) {
    if (err){
      console.log('ERROR:');
      console.log(err);
    }
    else{
      console.log('Image uploaded!');
      console.log('Now tweeting it...');

      T.post('statuses/update', {
        /* You can include text with your image as well. */            
        // status: 'New picture!', 
        /* Or you can pick random text from an array. */            
        status: random_from_array([
          'New picture!',
          'Check this out!'
        ]),
        media_ids: new Array(data.media_id_string)
      },
        function(err, data, response) {
          if (err){
            console.log('ERROR:');
            console.log(err);
          }
          else{
            console.log('Posted an image!');
          }
        }
      );
    }
  });
}


fs.readdir(__dirname + '/images', function(err, files) {
  if (err){
    console.log(err);
  }
  else{
    var images = [];
    files.forEach(function(f) {
      images.push(f);
    });

  /*
    You have two options here. Either you will keep your bot running, and upload images using setInterval (see below; 10000 means '10 milliseconds', or 10 seconds), --
  */
    setInterval(function(){
      upload_random_image(images);
    }, 30000);

  /*
    Or you could use cron (code.tutsplus.com/tutorials/scheduling-tasks-with-cron-jobs--net-8800), in which case you just need:
  */

    // upload_random_image(images);
  }
});