<div class="container">
  <div class="label" id="#label">1</div>
  <div class="border">
    <div id="#progress" class="progress"></div>
  </div>
  <div class="buttons-group">
    <button class="button" id="#resume">Resume</button>
    <button class="button disabled" id="#pause">Pause</button>
    <button class="button disabled" id="#reset">Reset</button>
  </div>
</div>

@keyframes animation {
  from {
    width: 100%;
  }
  to {
    width: 0%;
  }
}

body {
  display: flex;
  align-items: center;
  justify-content: center;
  height: 100vh;
}

.container {
  display: flex;
  flex-direction: column;
  width: 500px;
}

.label {
  font-size: 100px;
  line-height: 0.9;
}

.border {
  border: 2px solid #f2f2f2;
}

.progress {
  height: 10px;
  background-color: black;
}

.animate {
  animation-name: animation;
  animation-iteration-count: infinite;
  animation-timing-function: linear;
}

.pause {
  animation-play-state: paused;
}

.buttons-group {
  display: flex;
  margin-top: 20px;
}

.button {
  border: 1px solid #000;
  color: #000;
  padding: 10px 20px;
  margin: 0 20px 0 0;
  text-transform: uppercase;
  cursor: pointer;
}

button:active {
  transform: translate3d(1px, 1px, 0);
}

.disabled {
  opacity: 0.5;
  pointer-events: none;
}

(function () {
  var delay = 3000;

  var label = document.getElementById("#label");
  var value = parseInt(label.textContent);

  var progress = document.getElementById("#progress");

  var resumeBtn = document.getElementById("#resume");
  var pauseBtn = document.getElementById("#pause");
  var resetBtn = document.getElementById("#reset");

  var t = new timer(function () {
    label.textContent = ++value;
  }, delay);

  progress.style.animationDuration = delay + "ms";

  resumeBtn.addEventListener("click", function () {
    t.resume();

    pauseBtn.classList.remove("disabled");
    resumeBtn.classList.add("disabled");
    resetBtn.classList.add("disabled");

    progress.classList.add("animate");
    progress.classList.remove("pause");
  });

  pauseBtn.addEventListener("click", function () {
    t.pause();

    pauseBtn.classList.add("disabled");
    resumeBtn.classList.remove("disabled");
    resetBtn.classList.remove("disabled");

    progress.classList.add("pause");
  });

  resetBtn.addEventListener("click", function () {
    t.reset();

    pauseBtn.classList.add("disabled");
    resumeBtn.classList.remove("disabled");
    resetBtn.classList.add("disabled");

    // https://css-tricks.com/restart-css-animation/
    progress.classList.remove("animate");
    void progress.offsetWidth;
    progress.classList.add("animate");
  });
})();

function timer(callback, delay) {
  var timerId;
  var start;
  var remaining = delay;

  this.pause = function () {
    window.clearTimeout(timerId);
    remaining -= new Date() - start;
  };

  var resume = function () {
    start = new Date();
    timerId = window.setTimeout(function () {
      remaining = delay;
      resume();
      callback();
    }, remaining);
  };
  this.resume = resume;

  this.reset = function () {
    remaining = delay;
  };
}