How to create a countdown timer with JavaScript?

Javascript Web Development Object Oriented Programming

To create a countdown timer with JavaScript, the code is as follows −

Example

<!DOCTYPE html>
<html>
<head>
<meta name="viewport" content="width=device-width, initial-scale=1" />
<style>
   body {
      font-family: "Segoe UI", Tahoma, Geneva, Verdana, sans-serif;
   }
   .timer {
      text-align: center;
      font-size: 60px;
      margin-top: 0px;
      color: white;
      background-color: rgb(100, 38, 214);
   }
</style>
</head>
<body>
<h1 style="text-align: center;">Countdown Timer Example</h1>
<h2 class="timer"></h2>
<script>
   var countDownDate = new Date("June 5, 2022 11:27:15").getTime();
   var timeClear = setInterval(function() {
      var now = new Date().getTime();
      var timeLeft = countDownDate - now;
      var days = Math.floor(timeLeft / (1000 * 60 * 60 * 24));
      var hours = Math.floor(
         (timeLeft % (1000 * 60 * 60 * 24)) / (1000 * 60 * 60)
      );
      var minutes = Math.floor((timeLeft % (1000 * 60 * 60)) / (1000 * 60));
      var seconds = Math.floor((timeLeft % (1000 * 60)) / 1000);
      document.querySelector(".timer").innerHTML = days + "d " + hours + "h " + minutes + "m " + seconds + "s ";
      if (timeLeft < 0) {
         clearInterval(timeClear);
         document.querySelector(".timer").innerHTML = "Timer Finished";
      }
   }, 1000);
</script>
</body>
</html>