Google Script to check Packt free book

checkBook.gs

/*
 The purpose of this script is to daily check Packt's Free Book offer 
 and notify via e-mail with the title of the book and link to download page
 -> https://www.packtpub.com/packt/offers/free-learning
 
 Author: Douglas Matoso - www.dmatoso.com
 
 Instructions:
 1) Create a new Google Script at http://script.google.com
 2) Paste the code below, putting your email in the "email" var.
 3) Execute the checkBook function to test (the script may ask an one time permission)
 4) Check your mailbox.
 5) If it's working, you can schedule it to run daily. 
    Click the clock icon (Project's current triggers) and add a new trigger with options:
    Funcion: checkBook, Time-driven, Day timer, 7am to 8am (or choose a different time to receive the daily email)
*/

function checkBook() {
  var url = "https://www.packtpub.com/packt/offers/free-learning";
  var email = "[your e-mail here]";
  var page = UrlFetchApp.fetch(url);
  var doc = Xml.parse(page, true);
  var bodyHtml = doc.html.body.toXmlString();
  doc = XmlService.parse(bodyHtml);
  var html = doc.getRootElement();
  var title = getElementsByClassName(html, 'dotd-title')[0].getChild('h2').getText();

  MailApp.sendEmail({
     to: email,
     subject: "Packt Free Book",
    htmlBody: "Title: " + title + "<br><br>" + url
   });
}


function getElementsByClassName(element, classToFind) {  
  var data = [];
  var descendants = element.getDescendants();
  descendants.push(element);  
  for(i in descendants) {
    var elt = descendants[i].asElement();
    if(elt != null) {
      var classes = elt.getAttribute('class');
      if(classes != null) {
        classes = classes.getValue();
        if(classes == classToFind) data.push(elt);
        else {
          classes = classes.split(' ');
          for(j in classes) {
            if(classes[j] == classToFind) {
              data.push(elt);
              break;
            }
          }
        }
      }
    }
  }
  return data;
}