How to prevent countdown timer from resetting when webpage is refreshed?

Question

I am designing a website and I integrated a 5 minute countdown timer that starts when the web-page is loaded, using JavaScript. However, since I am more of a designer than a developer, I don't know how to edit the JavaScript code to make it so that the timer does not restart when the webpage is reloaded. I know I have to store the users cookies, and I've searched online, but the javascript code didnt work when I inserted the code. Would anyone here be able to help me out? Thank you!

Here is the javascript code for the 5 minute timer:

function startTimer(duration, display) {
var timer = duration, minutes, seconds;
setInterval(function () {
    minutes = parseInt(timer / 60, 10)
    seconds = parseInt(timer % 60, 10);

    minutes = minutes < 10 ? "0" + minutes : minutes;
    seconds = seconds < 10 ? "0" + seconds : seconds;

    display.textContent = minutes + " " + " " + seconds;

    if (--timer < 0) {
        timer = duration;
    }
}, 1000);
}

window.onload = function () {
var fiveMinutes = 60 * 5,
    display = document.querySelector('#time');
startTimer(fiveMinutes, display);
};

Answer 1

Check this approach where the time is stored in local storage of the browser and hence on refresh will not reset:

:HTML CODE:

<div id="time">

</div>

:JS CODE:

function startTimer(duration, display) {
var timer = duration, minutes, seconds;
setInterval(function () {
    minutes = parseInt(timer / 60, 10)
    seconds = parseInt(timer % 60, 10);

    minutes = minutes < 10 ? "0" + minutes : minutes;
    seconds = seconds < 10 ? "0" + seconds : seconds;

    display.textContent = minutes + " " + " " + seconds;

    if (--timer < 0) {
        timer = duration;
    }
  console.log(parseInt(seconds))
  window.localStorage.setItem("seconds",seconds)
  window.localStorage.setItem("minutes",minutes)
}, 1000);
}

window.onload = function () {
  sec  = parseInt(window.localStorage.getItem("seconds"))
  min = parseInt(window.localStorage.getItem("minutes"))

  if(parseInt(min*sec)){
    var fiveMinutes = (parseInt(min*60)+sec);
  }else{
    var fiveMinutes = 60 * 5;
  }
    // var fiveMinutes = 60 * 5;
  display = document.querySelector('#time');
  startTimer(fiveMinutes, display);
};

Here is the working model of the same in the codepen https://codepen.io/anon/pen/GymRNV?editors=1011

P.S: couldn't use it here as it is a sandbox and cant access localstorage.