JSFiddle - React, Tailwind, and code Playground

HTML

<link rel="stylesheet" href="http://ajax.googleapis.com/ajax/libs/jqueryui/1.8.4/themes/ui-lightness/jquery-ui.css">
<form name = "f1">
    <input type = "radio" Name = "r1" Value = "ON" onClick="GetSelectedItem(this)">On
    <input type = "radio" Name = "r1" Value = "OFF" onClick ="GetSelectedItem(this)">Off
</form>

<div id="output"></div>

JavaScript

var output = document.getElementById('output');

function GetSelectedItem(el) {
    output.innerHTML = el.value;
}