倒数计时器使用服务器时间PHP和Laravel

Question

I have a simple JS code to do countdown on the Client browser but there is a short coming the timer depends on the client machine so i want to get the Current Time and elapsed time from the Server.

Below is my working but it doesn't work.

function getTimeRemaining(endtime) {
          var t = Date.parse(endtime) - Date.parse(current_time);
          var seconds = Math.floor((t / 1000) % 60);
          var minutes = Math.floor((t / 1000 / 60) % 60);
          var hours = Math.floor((t / (1000 * 60 * 60)) % 24);
          var days = Math.floor(t / (1000 * 60 * 60 * 24));
          return {
            'total': t,
            'days': days,
            'hours': hours,
            'minutes': minutes,
            'seconds': seconds
          };
        }

        function initializeClock(id, endtime, current_time) {
          var clock = document.getElementById(id);
          var daysSpan = clock.querySelector('.days');
          var hoursSpan = clock.querySelector('.hours');
          var minutesSpan = clock.querySelector('.minutes');
          var secondsSpan = clock.querySelector('.seconds');

          function updateClock() {
            var t = getTimeRemaining(endtime, current_time);

            daysSpan.innerHTML = t.days;
            hoursSpan.innerHTML = ('0' + t.hours).slice(-2);
            minutesSpan.innerHTML = ('0' + t.minutes).slice(-2);
            secondsSpan.innerHTML = ('0' + t.seconds).slice(-2);

            if (t.total <= 0) {
              clearInterval(timeinterval);
              $('#clockdiv').html('You can\'t Reserve anymore')
            }
          }

          updateClock();
          var timeinterval = setInterval(updateClock, 1000);
        }

        var deadline = '2017-02-24 18:12:29';
        var current_time = new EventSource('Server/script/example.php');

            current_time.onopen = function(event) {
                //console.log(event)
                current_time.onmessage = function(event) 
                {
                     return event.data;

                }
                current_time.onerror = function (error) {
                    //console.log('we have an error')
                }
            }
            console.log(current_time)


        initializeClock('clockdiv', deadline, current_time); 

So am trying to use HTML SSE server Sent Event so as Listen to response instead of making the request.

current_time variable is empty and the output of the Time is NAN NAN NAN

So is there a better of achieving the above or can some work this code for me.