andruxxa,
<!DOCTYPE HTML>
<html>
<head>
<title>Untitled</title>
<meta charset="utf-8">
<script src="http://ajax.googleapis.com/ajax/libs/jquery/1.11.0/jquery.min.js"></script>
<script>
jQuery(document).ready(function($) {
$('.quont-minus').click(function () {
var $input = $(this).parent().find('input');
var val = +$input[0].defaultValue;
var count = parseInt($input.val()) - val;
count = count < val ? val : count;
$input.val(count);
$input.change();
return false;
});
$('.quont-plus').click(function () {
var $input = $(this).parent().find('input');
var val = +$input[0].defaultValue;
$input.val(parseInt($input.val()) + val);
$input.change();
return false;
});
});
</script>
</head>
<body>
<div class="opt-quontity">
<span class="quont-minus btn">-</span>
<input type="text" value="5">
<span class="quont-plus btn">+</span>
</div> <!-- .opt-quontity -->
</body>
</html>