Question

I want to stop this timer when I end the exam, but before it reaches zero. Kindly help me out on scripts please. Thanks.

JavaScript code:

var cnt = 165*60; // 165 minutes (2 hours & 45 minutes) convert to seconds

function countdown() {
    if (cnt < 0) {
        document.f.c.value = "- : - - : - -" ;
    }
    else {
        hour = Math.floor(cnt / 3600);
        totalmin = Math.floor(cnt / 60);
        min = totalmin - (hour * 60);
        sec = cnt - (totalmin * 60);
        if (sec < 10) { sec = "0" + sec;}
        if (min < 10) {min = "0" + min;}
        if (hour < 10) {hour = "0" + hour;}
        document.f.c.value = hour + ":" + min + ":" + sec;
        cnt--;
        _timer = setTimeout("countdown()", 1000);
    }
}

var _timer = setTimeout("countdown()", 1000); // tick

Answer 1

I assume you meant that you want to end the timer before the countdown reaches 0.

First of all, you should use setInterval instead. It should work in all major browsers (including IE). It is just a slightly nicer way to express “I want this to happen every so often.” According to the MDN, it:

Calls a function repeatedly, with a fixed time delay between each call to that function.

Here’s how you would use it:

var cnt = 165*60; // 165 minutes (2 hours & 45 minutes) convert to seconds
function countdown() {
  if (cnt < 0) {
   document.f.c.value = "- : - - : - -" ;
  }
  else {
   hour = Math.floor(cnt / 3600);
   totalmin = Math.floor(cnt / 60);
   min = totalmin - (hour * 60);
   sec = cnt - (totalmin * 60);
   if (sec < 10) {sec = "0" + sec;}
   if (min < 10) {min = "0" + min;}
   if (hour < 10) {hour = "0" + hour;}
   document.f.c.value = hour + ":" + min + ":" + sec;
   cnt--;

   if(cnt <= 0) { # Stops the timer when it reaches 0.
       clearInterval(_interval);
   }
  }
}
var _interval = setInterval(countdown, 1000);

And somewhere in your page have a button that will stop the timer.

<input type="button" value="Done" onclick="clearInterval(_interval)">

Although to be honest, having a countdown timer freaks me out. I’d rather have a count-up timer. 🙂