javascript - 读取单选按钮的值时，值未定义

Question

我正在尝试获取所选单选按钮的值。我尝试了以下方法，但我得到的值为 undefined .

var nameSelected;
$('.m-radio-inline input').on("change", function() {
  nameSelected = $('input[name="abc"]:checked').val();
});
alert(nameSelected);

<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<div class="m-radio-inline">
  <label class="m-radio">
    <input type="radio" name="abc"  value="Ash" checked> 
    Ash
    <span></span>
  </label>
  <label class="m-radio">
    <input type="radio" name="abc"  value="Win"> 
    Win
    <span></span>
  </label>
</div>

它应该给 Ash/Win

Answer 1

因为它在 nameSelected 具有值之前发出警报 - 将 alert 放入 change 处理程序中:

var nameSelected;
$('.m-radio-inline input').on("change", function() {
  nameSelected = $('input[name="abc"]:checked').val();
  alert(nameSelected);
});

<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<div class="m-radio-inline">
  <label class="m-radio">
	<input type="radio" name="abc"  value="Ash" checked>Ash
	<span></span>
  </label>
  <label class="m-radio">
       <input type="radio" name="abc"  value="Win">Win
       <span></span>
  </label>
</div>