如何确定 JavaScript 中 RadioButtonList 的 SelectedValue?

How can I determine the SelectedValue of a RadioButtonList in JavaScript?(如何确定 JavaScript 中 RadioButtonList 的 SelectedValue?)

问题描述

我有一个带有数据绑定 RadioButtonList 的 ASP.NET 网页.我不知道在设计时会渲染多少单选按钮.我需要通过 JavaScript 确定客户端上的 SelectedValue.我尝试了以下方法，但运气不佳:

I have an ASP.NET web page with a databound RadioButtonList. I do not know how many radio buttons will be rendered at design time. I need to determine the SelectedValue on the client via JavaScript. I've tried the following without much luck:

var reasonCode = document.getElementById("RadioButtonList1");
var answer = reasonCode.SelectedValue;  

(答案"被返回为未定义")请原谅我对 JavaScript 的无知，但我做错了什么?

("answer" is being returned as "undefined") Please forgive my JavaScript ignorance, but what am I doing wrong?

提前致谢.

推荐答案

ASP.NET 围绕实际的无线电输入呈现一个表格和一堆其他标记.以下应该有效:-

ASP.NET renders a table and a bunch of other mark-up around the actual radio inputs. The following should work:-

 var list = document.getElementById("radios"); //Client ID of the radiolist
 var inputs = list.getElementsByTagName("input");
 var selected;
 for (var i = 0; i < inputs.length; i++) {
      if (inputs[i].checked) {
          selected = inputs[i];
          break;
       }
  }
  if (selected) {
       alert(selected.value);
  }

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