JSFiddle - React, Tailwind, and code Playground

HTML

<input type="radio" name="link" value="one">One
<input type="radio" name="link" value="two" checked="checked">Two
<input type="radio" name="link" value="three">Three
    
<input type="button" value="OK" id="ok_button">

JavaScript

var btn = document.getElementById('ok_button');
btn.addEventListener('click', function(){
    var dt = document.querySelector('[name="link"]:checked').value;
    alert('/testfolder/' + dt)
})