购物车加减值，只取正整数值

<input name="" type="button" value="-" onclick="onChan('jian','1')"/>
<input id="kk1" name="" type="text" max="5" value="1" onkeyup="onChan()" />
<input name="" type="button" value="+" onclick="onChan('add','1')"/>

<input name="" type="button" value="-" onclick="onChan('jian','2')"/>
<input id="kk2" name="" type="text" max="5" value="1" onkeyup="onChan()" />
<input name="" type="button" value="+" onclick="onChan('add','2')"/>

<script type="text/javascript" src="jquery-1.7.2.min.js"></script>
<script>
function onChan(obj,obj2) {
        var reg=new RegExp("[0-9]+");

        //+-操作
         var addJian = $('#kk'+obj2).val()*1;
        if(obj == "add"){
             var maxnum = $('#kk'+obj2).attr("max")*1;
             if(reg.test(addJian)){
                 if(addJian<maxnum){   
                    $('#kk'+obj2).val(addJian+1);
                 }
             }else{ 
                    $('#kk'+obj2).val(0);
             }
        }
        if(obj == "jian"){
            if(addJian != "0" && reg.test(addJian)){
                $('#kk'+obj2).val(addJian-1);
            }
        }
        var nn = $("input[id*=kk]");
        $.each(nn, function(i,o) {
            var mm = $(o).val(); //数量
            if (isNaN(mm)) {
                mm=mm.replace(/[^\d]/g,'');
                $(o).val(mm);
            }
            if (mm == 0) {
                return true;
            }
　　　　　　var maxnum = $(o).attr("max")*1;
            if(mm > maxnum){
                $(o).val(maxnum);
                mm = maxnum;
            }
            })
        }
</script>