mapit - background.js (events are added or removed)

background.js and content.js (events are added or removed)

//background.js
chrome.runtime.onInstalled.addListener(
  function () {
    chrome.alarms.create("gcgmalarm",{when: Date.now() + 10*1000,periodInMinutes: 2});
  });

function alarmcount(callback) {
    var count; 
    chrome.alarms.getAll(function(alarms) { callback(alarms.length) }); 
}

function myDate() {
  var now = new Date();
  var now2 = now.getMonth()+1 + "/" + now.getDate() + "/" + now.getFullYear() + " " + now.getHours() + ":" + now.getMinutes() + ":" + now.getSeconds();
  return now2;  
}

chrome.alarms.onAlarm.addListener(function (){ AreYouAround();});
function AreYouAround() {
  chrome.tabs.query({active: true, currentWindow: true}, function(tabs) {
    chrome.tabs.sendMessage(tabs[0].id, {action: "checking", now:myDate()}, function(response) {});
    alarmcount(function(count) { 
      var numAlarms = count;
      var msg = "alarm count=" + numAlarms;
      chrome.tabs.sendMessage(tabs[0].id, {action: "console",consolelog:msg}, function(response) {}); 
    });
  });
};


//content.js
//Is the extension working? polling from backend
 if (msg.action == 'checking') {
    var t1 = document.getElementsByClassName('lv-location');
    var t2 = document.getElementsByClassName('calendar-clicksaver-maplink');
    if (DEBUG === true) { console.log(msg.now, ": checking....");}
    if (t1.length != t2.length){
      if (DEBUG === true) { console.log("links missing ... updating DOM");}
      Start();
    }
  }
});