在JS上怎么取Repeater控件的值

    我初学C#不久，请教下在JS上怎么取Repeater控件的值，我要实现lblnew_package_qty=txtnew_applyqty /lblnew_serial_qty。写在JS的callQty(this)里面。        function callQty(txtvalue) {            if (!isInteger(txtvalue.value)) {
                alert("请输入有效数字!");
                txtvalue.focus();
                txtvalue.value = "";
                return false;
            }
            
            lblnew_package_qty.value = parseFloat(parseFloat(txtvalue.value) /   ？（lblnew_serial_qty 这个值该怎么取？）
           
            
        }Repeater页面代码：
<td>
    <input value='<%# string.Format("{0:0}", Eval("new_applyqty")) %>' runat="server"
        class="text" style="text-align: right; width: 40px;" type="text" onchange="callQty(this)" onfocus="this.select()" id="txtnew_applyqty" />
</td>
<td>
    <asp:Label ID="lblnew_serial_qty" runat="server" Text='<%#string.Format("{0:0.000}", Eval("new_serial_qty")) %>' />
</td>
<td>
    <asp:Label ID="lblnew_package_qty" runat="server" Text='<%#string.Format("{0:0.000}", Eval("new_package_qty")) %>' />
</td>