JSFiddle - React, Tailwind, and code Playground
HTML
<label>Go To party</label><br />
<input type="radio" name="party" id="rsvpyes" value="yes" />Yes<br />
<input type="radio" name="party" id="rsvpno" value="no" />No<br />
<a href="mypage.asp?">RSVP</a>
JavaScript
$("input[name=party]").click(function(e){
e.preventDefault()
$(this).attr("href", window.location.href + "party="+$(":radio[name=party]:checked").val())
alert($(this).attr("href"))
})