This is a Google Apps Script to monitor dom elements at a website if they change you will get an email.

WebsiteWatcher.gs

function initSheets(sps){
    var Emailsheet;
  try{
    Emailsheet = sps.getSheetByName("emaillist");
  } catch(e){
    sps.insertSheet("emaillist")
    Emailsheet = sps.getSheetByName("emaillist");
    Emailsheet.getRange("A1").setValue("[email protected]")
    }
  
    var smssheet;
  try{
    smssheet = sps.getSheetByName("smslist");
  }catch(e){
    sps.insertSheet("smslist");
    smssheet = sps.getSheetByName("smslist");
    Emailsheet.getRange("A1").setValue("12345678910")
  }
  
    var wwwsheet;
  try{
    wwwsheet = sps.getSheetByName("wwwlist");
  }catch(e){
    sps.insertSheet("wwwlist");
    wwwsheet = sps.getSheetByName("wwwlist");
  }
}

function elementFetcher(url,startstring, endstring) {
  if(url != ""){
  var doc = UrlFetchApp.fetch(url).getContentText();
  var start = doc.search(startstring);
  var end = doc.search(endstring);
    Logger.log(start);
    Logger.log(end);
  var data = "";
  if((start || end) == -1){
    data = "No valid start or end found :("
  } else {
  data = doc.slice(start, end);
    Logger.log(data);
  }
    
    
    if(data.length > 10000){
    data = data.slice(0, 5000)
    }
  return data;
  }else {
    return "Error!"
  }
}


function onOpen(e){
  /*
  var newsps = SpreadsheetApp.create("Adresslist");
  var id = newsps.getId();
  var sps = SpreadsheetApp.openById(id);
  return sps;
  */
  try{
  SpreadsheetApp.getUi().createAddonMenu().addItem("Create Webwatcher", "start").addToUi();
  }catch(e){
  Logger.log(e);
  }
  
}

function sendEmail(sps, subject, body){
  var Emailsheet;
  try{
    Emailsheet = sps.getSheetByName("emaillist");
  } catch(e){
    sps.insertSheet("emaillist")
    Emailsheet = sps.getSheetByName("emaillist");
    }
  for(var i =1; i < 100; i++){
    var r = Emailsheet.getRange(i, 1);
    
    if(r.length < 4){break;}
    var data = r.getValue();
    Logger.log(data);
    GmailApp.sendEmail(data, subject, body)
  }
}

function sendSMS(sps, body){
  var smssheet;
  try{
    smssheet = sps.getSheetByName("smslist");
  }catch(e){
    sps.insertSheet("smslist");
    smssheet = sps.getSheetByName("smslist");
  }
  for(var i =1; i < 100; i++){
    var r = smssheet.getRange(i, 1);
    var data = r.getValue();
    //Must be done!!!!!!!!
  }
}

function crawlWebsites(sps){
  var wwwsheet;
  try{
    wwwsheet = sps.getSheetByName("wwwlist");
  }catch(e){
    sps.insertSheet("wwwlist");
    wwwsheet = sps.getSheetByName("wwwlist");
  }
  for(var i =1; i < 100; i++){
    var r = wwwsheet.getRange(i, 1);
    var wwwAdress = r.getValue();
    if (wwwAdress == ""){
      break;
    }
    r = wwwsheet.getRange(i, 2);
    var start = r.getValue();
    r = wwwsheet.getRange(i, 3);
    var end = r.getValue();
    r = wwwsheet.getRange(i, 4);
    var cache = r.getValue();
    //////Crawling and alert
    var tmpData = elementFetcher(wwwAdress, start, end);
    if(cache !== tmpData){
      r.setValue(tmpData);
      sendEmail(sps, "Change on: " + wwwAdress, tmpData);
      sendSMS(sps, "Change on: "+ wwwAdress);
    }
    
  }
}


function start(){
  var sps = SpreadsheetApp.getActive();
  initSheets(sps);
    crawlWebsites(sps);
}

function onInstall(e) {
  onOpen(e);
}