JSFiddle - React, Tailwind, and code Playground

HTML

<form id="quizful" class="form" action="" method="post">
            <div id="quiz-form-questions-container">
                <div id="question" class="form-group">
                    <h4 id="question-text" class="control-label"></h4>
                    <div id="answer"></div>
                </div>
            <div id="question-0" class="form-group"><h4 id="question-text" class="control-label">First Question</h4><div id="answer-0-0"><input name="answers0" value="0" type="checkbox">yes</div><div id="answer-0-1"><input name="answers0" value="1" type="checkbox">no</div></div><div id="question-1" class="form-group" style="display: none;"><h4 id="question-text" class="control-label">Second Question</h4><div id="answer-1-0"><input name="answers1" value="0" type="radio">yes</div><div id="answer-1-1"><input name="answers1" value="1" type="radio">no</div></div><div id="question-2" class="form-group" style="display: none;"><h4 id="question-text" class="control-label">Third Question</h4><div id="answer-2-0"><input name="answers2" value="0" type="radio">yes</div><div id="answer-2-1"><input name="answers2" value="1" type="radio">no</div></div></div>
            <div class="list-group">
                <button id="start-button" class="btn btn-success" style="display: none;"> Start</button>
                <button id="prev-button" class="btn btn-primary" style="display: none;"> &lt;&lt;</button>
                <button id="next-button" class="btn btn-primary" style=""> &gt;&gt;</button>
                <button type="submit" id="finish-button" class="btn btn-primary" style="display:none;"> Finish</button>
            </div>
        </form>

JavaScript

console.log(document.forms.quizful);
 var formData = new FormData(document.forms.quizful);
 console.log(formData.getAll("answers2"));
 formData.append("username", "Groucho");
 console.log(formData.getAll("username"));