Google App Script の自動フォロー，DM script <This script is under The MIT License. | The MIT License にて>

main.gs

'use strict';

// OAuth1認証用インスタンス
var twitter = TwitterWebService.getInstance(
  'consumer_key',
  'consumer_secret'
);

//OAuth1ライブラリを導入したうえで、getServiceを上書き
twitter.getService = function() {
  return OAuth1.createService('Twitter2')
    .setAccessTokenUrl('https://api.twitter.com/oauth/access_token')
    .setRequestTokenUrl('https://api.twitter.com/oauth/request_token')
    .setAuthorizationUrl('https://api.twitter.com/oauth/authorize')
    .setConsumerKey(twitter.consumer_key)
    .setConsumerSecret(twitter.consumer_secret)
    .setCallbackFunction('authCallback')
    .setPropertyStore(PropertiesService.getUserProperties())
}

// 認証を行う（必須）
function authorize() {
  var url = twitter.authorize();
  Logger.log(url);
}

// 認証をリセット
function reset() {
  twitter.reset();
}

// 認証後のコールバック（必須）
function authCallback(request) {
  return twitter.authCallback(request);
}

function onFormSent(e) {
  var itemResponses = e.response.getItemResponses();
  var twitterId = '';
  for (var i = 0; i < itemResponses.length; i++) {
    var itemResponse = itemResponses[i];
    var question = itemResponse.getItem().getTitle();
    if (question.indexOf('Twitter') > -1) {
      twitterId = itemResponse.getResponse();
    }
  }
  Logger.log(twitterId);
  follow(twitterId);
  sentMessage(twitterId);
}

function follow(sn) {
  var service   = twitter.getService();
  var formData  = {
    'screen_name': sn,
    'follow':      true,
  };
  var options  = {
    'method' : 'post',
    'payload' : formData
  };
  var json      = service.fetch('https://api.twitter.com/1.1/friendships/create.json', options);
  var response  = JSON.parse(json);
}

function sentMessage(sn) {
  var service   = twitter.getService();
  var formData  = {
    'screen_name': sn,
    'text':        'DM文',
  };
  var options  = {
    'method' : 'post',
    'payload' : formData
  };
  var json      = service.fetch('https://api.twitter.com/1.1/direct_messages/new.json', options);
  var response  = JSON.parse(json);
}