freeCodeCamp/guide/english/javascript/tutorials/how-to-create-a-countdown-timer/index.md

title
How to Create a Countdown Timer

How to Create a Countdown Timer

Creation

Start by building the countdownTimer function.

function startCountdown(seconds){
  var counter = seconds;

  var interval = setInterval(() => {
    console.log(counter);
    counter--;
    

    if(counter < 0 ){
      
      // The code here will run when
      // the timer has reached zero.
      
      clearInterval(interval);
      console.log('Ding!');
    };
  }, 1000);
};

Execution

Now to start the timer we provide startCountdown() with a number value as an argument which represents the seconds to countdown.

  startCountdown(10);
  // Console Output // 
  // 10
  // 9
  // 8
  // 7
  // 6
  // 5
  // 4
  // 3
  // 2
  // 1
  // 0 
  // Ding!

Live Example

Codepen - Countdown Timer

More Resources

Methods used:

• setInterval()
• clearInterval()