<body>
  <header>
    <h2 class="title">Date.prototype.getMilliseconds()</h2>
    <p class="description">Функція `updateTimer()` використовує `Date.prototype.getMilliseconds()` для відображення мілісекунд.</p>
  </header>
  <main>
    <div class="result">
      <div id="timer">00:00:00.000</div>
      <button onclick="startTimer()">Старт</button>
      <button onclick="stopTimer()">Стоп</button>
      <button onclick="resetTimer()">Скидання</button>
    </div>
  </main>
</body>

body {
  font-size: 16px;
  line-height: 1.5;
  font-family: monospace;
}

header {
  background-color: #f1f1f1;
  margin-bottom: 25px;
  padding: 15px;
  -webkit-box-shadow: 0px 0px 3px 0px rgba(118, 118, 118, 1);
  -moz-box-shadow: 0px 0px 3px 0px rgba(118, 118, 118, 1);
  box-shadow: 0px 0px 3px 0px rgba(118, 118, 118, 1);
}

header h2.title {
  padding-bottom: 15px;
  border-bottom: 1px solid #999;
}

header p.description {
  font-style: italic;
  color: #222;
}

.result {
  background-color: #f8f8f8;
  padding: 15px;
  -webkit-box-shadow: 0px 0px 3px 0px rgba(118, 118, 118, 1);
  -moz-box-shadow: 0px 0px 3px 0px rgba(118, 118, 118, 1);
  box-shadow: 0px 0px 3px 0px rgba(118, 118, 118, 1);
}

button {
  display: block;
  background-color: #4CAF50;
  color: white;
  padding: 14px 20px;
  margin: 8px 0;
  cursor: pointer;
  width: 100%;
}

p {
  margin-top: 20px;
  font-weight: bold;
}

let intervalId;
let startTime;

function startTimer() {
  if (!intervalId) {
    startTime = new Date().getTime();
    intervalId = setInterval(updateTimer, 1);
  }
}

function stopTimer() {
  clearInterval(intervalId);
  intervalId = null;
}

function resetTimer() {
  stopTimer();
  document.getElementById('timer').textContent = '00:00:00.000';
}

function updateTimer() {
  const currentTime = new Date().getTime();
  const elapsedTime = new Date(currentTime - startTime);
  
  const hours = String(elapsedTime.getUTCHours()).padStart(2, '0');
  const minutes = String(elapsedTime.getUTCMinutes()).padStart(2, '0');
  const seconds = String(elapsedTime.getUTCSeconds()).padStart(2, '0');
  const milliseconds = String(elapsedTime.getUTCMilliseconds()).padStart(3, '0');
  
  document.getElementById('timer').textContent = `${hours}:${minutes}:${seconds}.${milliseconds}`;
}

External CSS

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External JavaScript

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