[nerv_]

на скорую руку

<div id="box"></div>
<script>
	(function() {
		var startTime = new Date();
		var elem = document.getElementById( 'box' );
		var timer = setInterval( function() {
			var timeDifference = ( new Date() ) - startTime;
			if ( timeDifference > 10000 ) {
				clearInterval( timer );
				alert( 1 );
			} else {
				elem.innerHTML = timeDifference / 1000;
			}
		}, 1000 );
	})();
</script>