如何获取选定单选按钮的值?

I want to get the selected value from a group of radio buttons.

这是我的 HTML:

<div id="rates">
  <input type="radio" id="r1" name="rate" value="Fixed Rate"> Fixed Rate
  <input type="radio" id="r2" name="rate" value="Variable Rate"> Variable Rate
  <input type="radio" id="r3" name="rate" value="Multi Rate" checked="checked"> Multi Rate  
</div>

这是我的 js:

var rates = document.getElementById('rates').value;
var rate_value;
if(rates =='Fixed Rate'){
    rate_value = document.getElementById('r1').value;
    
}else if(rates =='Variable Rate'){
    rate_value = document.getElementById('r2').value;
    
}else if(rates =='Multi Rate'){
    rate_value = document.getElementById('r3').value;
}  

document.getElementById('results').innerHTML = rate_value;

我一直不确定.

推荐答案

var rates = document.getElementById('rates').value;

rates 元素是一个 div，所以它没有值.这可能是 undefined 的来源.

if (document.getElementById('r1').checked) {
  rate_value = document.getElementById('r1').value;
}

$("input[type='radio'][name='rate']:checked").val();