jq each的两种用法（笔记）

 <div class="cart_content"  th:each="oIdList:${orderIdList}">
        <table>
            <tr class="table_head">
                <th>订单号</th>
                <th colspan="3">商品</th>
                <th>商品金额</th>
                <th>商品数量</th>
                <th>总金额</th>
            </tr>
            <tr><td  rowspan="0"><span th:text="${oIdList}"></span></td></tr>
            <tr class="table_content" th:each="o:${orderList}" th:if="${oIdList}==${o.id}" >
                <td class="show_img">
                    <img th:src="${o.image}"  th:value="${o.sid}"
                         th:title="${o.name}"/>
                </td>
                <td class="title" colspan="2"><span th:text="${o.name}">商品名字</span></td>
                <td class="cost">￥<span th:text="${o.price}">20.00</span>元</td>
                <td class="count"><span class="minus">-</span><span class="number" th:text="${o.quantity}">2</span><span class="add">+</span>
                </td>
                <td class="per_sum">￥<span th:with="sum=${o.price}*${o.quantity}" th:text="${sum}">40.00</span>元</td>
            </tr>
            <tr  class="table_content_del_img">
                <td class="delete_img" rowspan="0"><img th:src="@{img/delete_icon.jpg}" th:value="${oIdList}" class="deleteShopCar"/>删除订单</td>
            </tr>
            <tr class="end_pay">
<!--                <td class="is_all"><input id="all" type="checkbox" checked="checked"/>全选</td>-->
<!--                <td class="space" colspan="3"></td>-->
                <td colspan="4" class="all_sum">总价：￥<span>500.00</span>元</td>
                <td colspan="1" class="pay_button_div">
                    <button class="pay_button">结算</button>
                </td>
            </tr>
        </table>
    </div>
<script>
    function calSum() {
        var sum = 0;
        $('.cart_content').each(function(){
           // console.log($(this));
            let arr_tr = $(this).find(".per_sum").children("span");
            let  sum=0;
            $.each(arr_tr,function (index,domEle) {
                console.log("index: domEle:",index,domEle.innerText);
                sum+=parseFloat(domEle.innerText);
            })
            sum = returnFloat(sum);   //保留两位小数
           console.log("sum:",sum);
            // //给赋值
            $(this).find('.end_pay').children(".all_sum").children("span").text(sum);

        })
</script>

$('.cart_content').each(function(){} 遍历class名为.cart_content的div块。
$.each(arr_tr,function (index,domEle) {} 遍历jq集合对象，注意domEle是js对象，而不是jq。