Count Down JavaScript library is a super tiny jQuery countdown timer plugin that counts down from a specific time (in seconds) to zero.
When the countdown reaches zero, a callback function is called, which is great for redirecting the current page to another URL or showing a message to the users.

countDown.js Implementation

Insert jQuery library and the countDown.js plugin into the webpage.

Create a container to hold the countdown timer

Initialize the countdown timer and specify the starting time the plugin should countdown from

$("#countDown").countdownTimer({
  // default: 10
  time: 100,
});

Execute a callback function when the time is up

$("#countDown").countdownTimer({
  time: 100,
  callback: function () {
    alert("Time's up!");
  },
});