How to create an accurate timer in javascript?

Question

I need to create a simple but accurate timer.

This is my code:

var seconds = 0;
setInterval(function() {
timer.innerHTML = seconds++;
}, 1000);
         


        

Answer 1

Doesn't get much more accurate than this.

var seconds = new Date().getTime(), last = seconds,

intrvl = setInterval(function() {
    var now = new Date().getTime();

    if(now - last > 5){
        if(confirm("Delay registered, terminate?")){
            clearInterval(intrvl);
            return;
        }
    }

    last = now;
    timer.innerHTML = now - seconds;

}, 333);

As to why it is not accurate, I would guess that the machine is busy doing other things, slowing down a little on each iteration adds up, as you see.