Javascript实现页面商品个数增减功能

效果

后台返回代码

Map cart = new HashMap();
cart.put(new GoodsVO(1001,"苹果",100),5);
cart.put(new GoodsVO(1002,"桔子",300),3);
cart.put(new GoodsVO(1003,"香蕉",150),3);
request.getSession().setAttribute("cat",cart);

前端页面

	
        ${item.key.name}
        
            -
            
            +
            
        
    





    //购买商品数量减1
    $(".subSpan").click(function () {
        let subSpanId = $(this).attr("id");
        let id = subSpanId.substring(7);
        let amount = $("#amountInput" + id).val();
        if (amount - 1  stock) {
            alert("所购商品数量不能大于库存");
            return;
        }
        $("#amountInput" + id).val(amount + 1);
    })