sprigan,
<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>