<input type=text name='ct_qty' id='ct_qty' value='1' size=4 maxlength=4 class=ed autocomplete='off' style='text-align:right;' onkeyup='calc_amount()'>
<img src='img/qty_control.gif' border=0 align=absmiddle usemap="#qty_control_map"> 개
<map name="qty_control_map">
<area shape="rect" coords="0, 0, 10, 9"   id='qty_plus'>
<area shape="rect" coords="0, 10, 10, 19" id='qty_minus'>
</map>

... 중략 ...


<script>
// 위,아래 이미지 클릭으로 수량 조절
$(document).ready(function() {
    var $this = $('#ct_qty');
    $('#qty_plus').click(function() {
        if (isNaN(parseInt($this.val()))) {
            $this.val(1);
        }
        else {
            $this.val(parseInt($this.val()) + 1);
        }
    }).css('cursor', 'pointer');

    $('#qty_minus').click(function() {
        if (isNaN(parseInt($this.val()))) {
            $this.val(1);
        }
        else {
            $this.val(parseInt($this.val()) - 1);
            if ($this.val() < 1) $this.val(1);
        }
    }).css('cursor', 'pointer');
});
</script>