Bravo,
может input type="number" и не мучатся?
<!DOCTYPE HTML>
<html>
<head>
<title>Untitled</title>
<meta charset="utf-8">
<style type="text/css">
.number-item a{
text-decoration: none;
}
</style>
<script src="http://ajax.googleapis.com/ajax/libs/jquery/1.11.0/jquery.min.js"></script>
<script>
jQuery(function($) {
$(".number-item").each(function(f, c) {
$(c).on("click", "a", function(e) {
var input = $("input", c)[0],
val = +input.value;
$(this).is(".plus-number-item") ? val++ : 1 < val && val--;
input.value = val;
e.preventDefault()
})
})
});
</script>
</head>
<body>
<div class="number-item">
<a href="#" class="minus-number-item">-</a>
<input type="text" value="1" />
<a href="#" class="plus-number-item">+</a></div>
</body>
</html>