StopWatch with HTML, CSS & JavaScript

01/16/2021

Demo

Video

Code

HTML

<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width,initial-scale=1">
    <title>StopWatch with HTML, CSS & JavaScript</title>
    <link rel="stylesheet" type="text/css" href="style.css">
  </head>
  <body>
    <div class="box">
      <div class="stopwatch">
        <span class="hours">00</span>
        <span>:</span>
        <span class="minutes">00</span>
        <span>:</span>
        <span class="seconds">00</span>
        <span>.</span>
        <span class="milliseconds">00</span>
      </div>
      <div class="buttons">
        <button class="btn start" onclick="startTimer()">Start</button>
        <button class="btn" onclick="stopTimer()">Stop</button>
        <button class="btn" onclick="resetTimer()">Reset</button>
      </div>
    </div>
    <script src="stopwatch.js"></script>
  </body>
</html>

CSS

@charset "utf-8";
@import url('https://fonts.googleapis.com/css2?family=Roboto:wght@400&display=swap');
* {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}
html {
  font-family: 'Roboto', sans-serif;
  font-size: 16px;
}
body {
  display: flex;
  justify-content: center;
  align-items: center;
  width: 100%;
  height: 100vh;
  background-color: #4eb4e1;
}
.box {
  display: flex;
  flex-direction: column;
  justify-content: center;
  align-items: center;
  width: 100%;
  max-width: 400px;
  padding: 10px;
}
.stopwatch {
  display: flex;
  justify-content: space-between;
  align-items: baseline;
  width: 100%;
  color: #fff;
  font-size: 4.5rem;
}
.milliseconds {
  font-size: 3rem;
}
.buttons {
  display: flex;
  justify-content: space-between;
  align-items: center;
  width: 100%;
  margin-top: 10px;
}
.btn {
  width: 30%;
  padding: 10px 0;
  border: none;
  border-radius: 4px;
  background-color: #e2ab1a;
  color: #fff;
  font-size: 1.25rem;
  font-family: inherit;
  outline: none;
  cursor: pointer;
}
.btn:disabled {
  background-color: #ccc;
  cursor: default;
}
@media screen and (max-width: 480px) {
  .stopwatch {
    font-size: 2.75rem;
  }
  .milliseconds {
    font-size: 2rem;
  }
}

JavaScript

let hr = min = sec = ms = 0;
let t;
let startBtn = document.querySelector(".start");

function countUp() {
  ms++;

  if (ms == 100) {
    sec++;
    ms = 0;
  }
  if (sec == 60) {
    min++;
    sec = 0;
  }
  if (min == 60) {
    hr++;
    min = 0;
  }
  displayTimer();
}
function displayTimer() {
  document.querySelector(".hours").innerHTML = ("0" + hr).slice(-2);
  document.querySelector(".minutes").innerHTML = ("0" + min).slice(-2);
  document.querySelector(".seconds").innerHTML = ("0" + sec).slice(-2);
  document.querySelector(".milliseconds").innerHTML = ("0" + ms).slice(-2);
}
function startTimer() {
  startBtn.disabled = true;
  t = setInterval(countUp, 10);
}
function stopTimer() {
  clearInterval(t);
  startBtn.disabled = false;
}
function resetTimer() {
  clearInterval(t);
  hr = min = sec = ms = 0;
  displayTimer();
  startBtn.disabled = false;
}