JavaScript counter that continue from where left

Question

I'm trying to create a countdown counter that should countdown for 24 hours, displaying the days, the hours, the minutes and the seconds. The question is that I want to make it somehow save the progress. For example, I put the countdown to start from now till tomorrow the same time (24 hours) and when a user comes in my site after 2 hours the counter should start from 22 hours for that user and if the user closes the site and then comes back after 2 hours the counter should start from 20 hours for that user. I hope it's clear enough. I found that if that is possible it could be done using cookies, but I'm not sure how it should be done... If anyone could help it will be great! :3 Here is my code so far: HTML:

<div id="clockdiv">
  <span class="days"></span>
  <span class="hours"></span>
  <span class="minutes"></span>
  <span class="seconds"></span>
</div>

JavaScript

// if there's a cookie with the name myClock, use that value as the deadline
    if(document.cookie && document.cookie.match('myClock')){
// get deadline value from cookie
    var deadline = document.cookie.match(/(^|;)myClock=([^;]+)/)[2];
    }

// otherwise, set a deadline 10 minutes from now and 
// save it in a cookie with that name
    else{
// create deadline 10 minutes from now
        var timeInMinutes = 1380;
        var currentTime = Date.parse(new Date());
        var deadline = new Date(currentTime + timeInMinutes*60*1000);

// store deadline in cookie for future reference
        document.cookie = 'myClock=' + deadline + '; path=/; domain=.optic2n.com';
    }

    function getTimeRemaining(endtime) {
      var t = Date.parse(endtime) - Date.parse(new Date());
      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) {
      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);

            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);
            }
        }

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

    initializeClock('clockdiv', deadline);

Thank you in advance for the help! :3

Best regards, Tsvetko Krastev

Answer 1

It is possible I have missed something, but your code seems very complex for something so simple. Here is what I came up with:

HTML:

<div id="clockdiv">
  <span id="d" class="days"></span>days
  <span id="h" class="hours"></span>hrs
  <span id="m" class="minutes"></span>mins
  <span id="s" class="seconds"></span>secs
</div>

Javascript:

var deadline = localStorage.getItem('dl') ? parseInt(localStorage.getItem('dl')) : (Date.now() + 86400000);
var delay = null;
// Good spot to do checks for 24hrs has passed already here

localStorage.setItem('dl',deadline);

function render() {
    if (delay) {
        clearTimeout(delay);
        delay = null;
    }
    var diff = (deadline - Date.now()) / 1000;
    document.getElementById('d').innerHTML = Math.floor(diff / 86400);
    document.getElementById('h').innerHTML = Math.floor(diff / 3600);
    document.getElementById('m').innerHTML = Math.floor((diff / 60) % 60);
    document.getElementById('s').innerHTML = Math.floor(diff % 60);
    delay = setTimeout(render,1000);
}
render();

NOTE: There are no checks for what to do after 24 hours.