JSFiddle - React, Tailwind, and code Playground

HTML

<body onload="init()">
    <h1>Javascript Quiz Application</h1>
    <div id="question"></div>
    <form id="answers" name="answers"></form>
    <div id="actions">
        <button id="next" onclick="showNextQuestion()">Next</button>
    </div>
    <div id="result"></div>
</body>

JavaScript

var allQuestions = [
    {
        question: "3*5",
        choices: ["1.5", "15", "12", "21"],
        correctAnswer: 1
    },
    {
        question: "5+3",
        choices: ["15", "7", "1", "8"],
        correctAnswer: 3
    },
    {
        question: "5-3",
        choices: ["2", "7", "16", "1.9"],
        correctAnswer: 0
    },
    {
        question: "5/2",
        choices: ["3", "2.6", "2.5", "9"],
        correctAnswer: 2
    }
];

var currentQuestionIndex = 0;
var results = [];

function init() {
    currentQuestionIndex = 0;
    results = [];
    showQuestion();
}

function showQuestion() {
    var questionObj = allQuestions[currentQuestionIndex];
    document.getElementById("question").innerHTML = questionObj.question;

    var radios = "";
    for(var i=0; i<questionObj.choices.length; ++i) {
        radios += "<input type='radio' name='answer' value='" +i +"' />" +questionObj.choices[i];
    }
    document.getElementById("answers").innerHTML = radios;
}

function checkAnswer() {
    var questionObj = allQuestions[currentQuestionIndex];
    var shouldBe = questionObj.correctAnswer;
    var selected = -1;
    for(var i=0; i<questionObj.choices.length; ++i) {
        if(document.answers.answer[i].checked) {
            selected = i;
            break;
        }
    }

    results[currentQuestionIndex] = shouldBe == selected;
}

function showNextQuestion() {
    checkAnswer();

    ++currentQuestionIndex;
    if(currentQuestionIndex == allQuestions.length) {
        showResult();
    } else {
        showQuestion();
    }
}

function showResult() {
    document.getElementById("question").innerHTML = "";
    document.getElementById("answers").innerHTML = "";
    document.getElementById("actions").innerHTML = "";

    var msg = "<h2>Results</h2>";
    var correctCount = 0;
    for(var i=0; i<results.length; ++i) {
        if(results[i]) {
            ++correctCount;
        }
        msg += "Question " +i +" " +results[i] + "<br>";
    }

    var...