javascript countdown timer with start & stop buttons

Question

I need to make a simple countdown timer from 5 to zero, with the buttons to START and STOP the counter. The only thing that I don\'t know is that why won\'t my counter stop.

Answer 1

myTimer is only in scope within the function. One solution is to make it global.

var myTimer;
function clock() {
     myTimer = setInterval(myClock, 1000);
     var c = 5;

     function myClock() {
       document.getElementById("demo").innerHTML = --c;
       if (c == 0) {
         clearInterval(myTimer);
         alert("Reached zero");
       }
     }
   }

5
Start counter
Stop counter