Which Radio button value selected in Javascript?

I thought this would be simple, and I'm sure it is, once one knows the trick..

I have some javascript that I want to run and check the value of some selections.. I have two Yes/No field set as Radio button.

The below works for basic field.. I want to do the same thing to see if Yes or No has been selected by the user on the Radio button.

$(document).on('knack-view-render.view_86', function(event, view, data) {
$("#view_86 .kn-button").on("click", function() {
if ($("#field_153").val() != "100.0000") {
alert ("Percentage total must equal 100%. Current value: " + Number($("#field_153").val()) + "%");
return false;

So I want something like this, but I already know that .val() returns undefined on these fields:

if ($("#field_418").val() == "Yes" && $("field_419").val() == "Yes") {
alert ("Field A and Field B cannot both be Yes");
return false;

The fields in the browser look like this: