<div class="more">+</div>
                    <input data-bind="attr: {
                           id: 'cart-item-'+item_id+'-qty',
                           'data-cart-item': item_id,
                           'data-item-qty': qty,
                           'data-cart-item-id': product_sku
                           }, value: qty"
                           type="number"
                           size="4"
                           class="item-qty cart-item-qty"
                           maxlength="12"/>
                    <div class="less">-</div>

jQuery('.more, .less').on("click",function(){
                var obj = jQuery(this);
                var currentQty = obj.siblings('.cart-item-qty').val();
                var iid = obj.siblings('.update-cart-item').attr('data-cart-item');

                if(obj.hasClass('more')){
                    var newAdd = parseInt(currentQty)+parseInt(1);
                    obj.siblings('.cart-item-qty').val(newAdd);
                    obj.siblings('.cart-item-qty').attr('data-item-qty',newAdd);
                    jQuery('#update-cart-item-'+iid).click();
                }else{
                   var newAdd = parseInt(currentQty)-parseInt(1);
                    obj.siblings('.cart-item-qty').val(newAdd);
                    obj.siblings('.cart-item-qty').attr('data-item-qty',newAdd);
                    jQuery('#update-cart-item-'+iid).click();
                }
            });