MixPetrov,
<!DOCTYPE html>
<html>
<head>
<title>Untitled</title>
<meta charset="utf-8">
<style type="text/css">
</style>
<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.12.4/jquery.min.js"></script>
<script>
$(function() {
function isright() {
var ns = +this.value.replace(/\D/g, "") || 0;
if (ns > 50) ns = 50;
if (ns < 10) ns = 10;
this.value = ns
}
var timer;
$(".num").on("input", function() {
window.clearTimeout(timer);
timer = window.setTimeout(isright.bind(this), 1200)
})
});
</script>
</head>
<body>
<input class="num">
<input class="num">
</body>
</html>