JSFiddle - React, Tailwind, and code Playground

HTML

<td style="vertical-align: top;">
    <input type="radio" value="1" name="Plan[packageId]">
    <label>3 Games</label>
    <br>
    <input type="radio" value="2" name="Plan[packageId]" checked="true">
    <label>5 Games</label>
    <br>
    <input type="radio" value="3" name="Plan[packageId]">
    <label>10 Games</label>
    <br>
</td>

JavaScript

var selectedPlan = $("input[name=Plan\\[packageId\\]]:checked").val();
alert(selectedPlan);