JSFiddle - React, Tailwind, and code Playground

HTML

<form name="form1">
    <b>Group 1:</b>
    <input type="radio" name="radio1" value="aaa" />
    <input type="radio" name="radio1" value="bbb" />
</form>

<form name="form2">
    <b>Group 2:</b>
    <input type="radio" name="radio2" value="aaa" />
</form>

<input type="button" onclick="get_checked_radio('radio1')" value="Check group 1" />
<input type="button" onclick="get_checked_radio('radio2')" value="Check group 2" />

JavaScript

function get_checked_radio(name)
{
    var radioElements = document.getElementsByName(name);
    for(var i=0; i < radioElements.length; i++)
    {
        if(radioElements[i].checked) 
        {
            alert("Radio button #" + (i+1) + " is checked");
            return;
        }
    }
                  
    alert("No radio button is checked");
}