跟踪任务所需的总时间

I am building a site where task is assigned to each user and he/she needs to complete the task within a fixed duration of time. For this is need to track Time taken on each task. I also need to track if the user is sitting idle on the site.

Right now i can do this using this code :

HTML

 <a class="btn btn-success btn-lg" id="startTracking" role="button">Start Tracking</a>
    <a class="btn btn-danger btn-lg" id="endTracking" role="button">Stop Tracking</a>
    <h2 id="testingSince"></h2>

JAVASCRIPT

<script type="text/JavaScript">
  var totalSeconds = 0;
  var idleSeconds = 0;
  $(document).ready(function () {
    $('body').on('click','#startTracking',function(){
      //Increment the idle time counter every minute.
      var idleInterval = setInterval(timerIncrement, 1000); // 1 second
    });

    //Zero the idle timer on mouse movement.
    $(this).mousemove(function (e) {
      idleSeconds = 0;
    });
    $(this).keypress(function (e) {
      idleSeconds = 0;
    });
  });

  function timerIncrement() {
    totalSeconds += 1;
    idleSeconds += 1 ;
    if (idleSeconds > 600) { // 20 minutes
      alert('You have been sitting Idle for 10 Minutes');
    }

    $('#testingSince').text(timeStringfromSeconds(totalSeconds));
  }

  function timeStringfromSeconds(totalSeconds){
      var hours = Math.floor(totalSeconds / 36e2),
      mins = Math.floor((totalSeconds % 36e2) / 60),
      secs = Math.floor((totalSeconds % 60));
      return ("0" + hours).slice(-2)+':'+("0" + mins).slice(-2)+':'+("0" + secs).slice(-2);
  }

 </script>

So this code works great and the user can see the time spent since he clicked the button. It also tracks user idle time and gives an alert after 10 minutes.

However the only Problem here is that when the page reloads the counter starts from 0. i.e the 2 lines :

var totalSeconds = 0;
var idleSeconds = 0;

I just want the timer counter not to restart and continue from its previous value.

One way of doing this is using Cookies. So i have to update them every second but i am not sure if this is a good Idea.

Please let me know if there is any other way or i need to use browser cookies ?

Many users will not permit cookies on their computers. You should never rely only on cookies. Maybe you should make some script that you can ajax call every second or two or five and store elapsed time in session.