JS实现商品购买数量加减
??????????????????? + "！");?
??????????? jQuery('#J_Tip').show();?
??????????? jQuery(obj).val(1);?
??????????? jQuery(obj).focus();?
??????? }?
??? }
??? function add(obj) {?
??????? var x = this.amount(obj, true);?
??????? var max = jQuery('#nAmount').val();?
??????? if (parseInt(x) <= parseInt(max)) {?
??????????? jQuery(obj).val(x);?
??????? } else {?
??????????? jQuery('#J_Tip').html("<i class="ico"></i>您所填写的商品数量超过库存！");?
??????????? jQuery('#J_Tip').show();?
??????????? jQuery(obj).val(max == 0 ? 1 : max);?
??????????? jQuery(obj).focus();?
??????? }?
??? }
??? function modify(obj) {?
??????? var x = jQuery(obj).val();?
??????? var max = jQuery('#nAmount').val();?
??????? if (!this.reg(parseInt(x))) {?
??????????? jQuery(obj).val(1);?
??????????? jQuery(obj).focus();?
??????????? jQuery('#J_Tip').html("<i class="ico"></i>请输入正确的数量！");?
??????????? jQuery('#J_Tip').show();?
??????????? return;?
??????? }?
??????? var intx = parseInt(x);?
??????? var intmax = parseInt(max);?
??????? if (intx < this.min) {?
??????????? jQuery('#J_Tip').html("<i class="ico"></i>商品数量最少为" + this.min?
??????????????????? + "！");?
??????????? jQuery('#J_Tip').show();?
??????????? jQuery(obj).val(this.min);?
??????????? jQuery(obj).focus();?
??????? } else if (intx > intmax) {?
??????????? jQuery('#J_Tip').html("<i class="ico"></i>您所填写的商品数量超过库存！");?
??????????? jQuery('#J_Tip').show();?
??????????? jQuery(obj).val(max == 0 ? 1 : max);?
??????????? jQuery(obj).focus();?
??????? }?
??? }
3、html代码：
??? ????? ??? <dt>
??? ????? ??? <span href="javascript:reduce('#J_Amount');">-</a>?
??? ??? ??????? <input name="J_Amount" id="J_Amount" type="text" maxlength="6" value="1" size="3" onkeyup="modify('#J_Amount');"/>?
??? ??? ??????? <a href="javascript:add('#J_Amount')">+</a>?
??? ??? ??????? <p id="J_Tip" style="display:none;"></p>?
??? ??? ??????? <input id="nAmount" type="hidden" value="1000"/>??? ????? ???
??? ????? ??? </dd>
