How to set one minute counter in javascript?

You could use something like this:

function gameLost() {
  alert("You lose!");
}
setTimeout(gameLost, 60000);

UPDATE: pass function reference to setTimeout() instead of code string (did I really write it that way? O_o)

---

EDIT

To display the timer too (improved version, thanks to davin too):

<button onclick="onTimer()">Clickme</button>
<div id="mycounter"></div>
<script>
i = 60;
function onTimer() {
  document.getElementById('mycounter').innerHTML = i;
  i--;
  if (i < 0) {
    alert('You lose!');
  }
  else {
    setTimeout(onTimer, 1000);
  }
}
</script>

......

You will want to use the setTimout function check out this article. https://developer.mozilla.org/En/Window.setTimeout Remember the timer is in milliseconds so for one minute is 60,000.

function timedOut() {
    alert("Some error message");
}

// set a timer
setTimeout( timedOut , 60000 );

That basically sets a timer that will execute the given function after 60.000 miliseconds = 60 seconds = 1 minute

Edit: here's a quick, imperfect fiddle that also shows the countdown http://jsfiddle.net/HRrYG

function countdown() {
    var seconds = 60;
    function tick() {
        var counter = document.getElementById("counter");
        seconds--;
        counter.innerHTML = "0:" + (seconds < 10 ? "0" : "") + String(seconds);
        if( seconds > 0 ) {
            setTimeout(tick, 1000);
        } else {
            alert("Game over");
        }
    }
    tick();
}

// start the countdown
countdown();