[sprigan]

Спасибо, то что нужно

<p id="ourclients"></p>
<script>
var startTime = "startTime" in localStorage ? localStorage.startTime : localStorage.startTime = Date.now();
Object.defineProperty(window, "clients", {
	get: function() {
		return Math.floor((Date.now() - startTime) / 1000 * 5);
	}
});

setInterval(function() {
	document.getElementById("ourclients").innerHTML = clients + " клиентов";
}, 100);
</script>