input[type="number"] plus/minus buttons

plusminus.html

<div id="field1">
    <button type="button" id="sub" class="sub">-</button>
    <input type="text" id="1" value="0" class="field" />
    <button type="button" id="add" class="add">+</button>
</div>

plusminus.js

$('.add').click(function () {
    $(this).prev().val(+$(this).prev().val() + 1);
});
$('.sub').click(function () {
    if ($(this).next().val() > 0) $(this).next().val(+$(this).next().val() - 1);
});