simple function to add quiz in javascript code example

Example 1: build a trivia and answer javascript

// code by webdevtrick (https://webdevtrick.com)
function Quiz(questions) {
    this.score = 0;
    this.questions = questions;
    this.questionIndex = 0;
}
 
Quiz.prototype.getQuestionIndex = function() {
    return this.questions[this.questionIndex];
}
 
Quiz.prototype.guess = function(answer) {
    if(this.getQuestionIndex().isCorrectAnswer(answer)) {
        this.score++;
    }
 
    this.questionIndex++;
}
 
Quiz.prototype.isEnded = function() {
    return this.questionIndex === this.questions.length;
}
 
 
function Question(text, choices, answer) {
    this.text = text;
    this.choices = choices;
    this.answer = answer;
}
 
Question.prototype.isCorrectAnswer = function(choice) {
    return this.answer === choice;
}
 
 
function populate() {
    if(quiz.isEnded()) {
        showScores();
    }
    else {
        // show question
        var element = document.getElementById("question");
        element.innerHTML = quiz.getQuestionIndex().text;
 
        // show options
        var choices = quiz.getQuestionIndex().choices;
        for(var i = 0; i < choices.length; i++) {
            var element = document.getElementById("choice" + i);
            element.innerHTML = choices[i];
            guess("btn" + i, choices[i]);
        }
 
        showProgress();
    }
};
 
function guess(id, guess) {
    var button = document.getElementById(id);
    button.onclick = function() {
        quiz.guess(guess);
        populate();
    }
};
 
 
function showProgress() {
    var currentQuestionNumber = quiz.questionIndex + 1;
    var element = document.getElementById("progress");
    element.innerHTML = "Question " + currentQuestionNumber + " of " + quiz.questions.length;
};
 
function showScores() {
    var gameOverHTML = "<h1>Result</h1>";
    gameOverHTML += "<h2 id='score'> Your scores: " + quiz.score + "</h2>";
    var element = document.getElementById("quiz");
    element.innerHTML = gameOverHTML;
};
 
// create questions here
var questions = [
    new Question("Hyper Text Markup Language Stand For?", ["JavaScript", "XHTML","CSS", "HTML"], "HTML"),
    new Question("Which language is used for styling web pages?", ["HTML", "JQuery", "CSS", "XML"], "CSS"),
    new Question("Which is not a JavaScript Framework?", ["Python Script", "JQuery","Django", "NodeJS"], "Django"),
    new Question("Which is used for Connect To Database?", ["PHP", "HTML", "JS", "All"], "PHP"),
    new Question("Webdevtrick.com is about..", ["Web Design", "Graphic Design", "SEO & Development", "All"], "All")
];
 
// create quiz
var quiz = new Quiz(questions);
 
// display quiz
populate();

Example 2: build a trivia and answer javascript

<!DOCTYPE html>
<!-- code by webdevtrick (https://webdevtrick.com) -->
<html>
<head lang="en">
    <meta charset="UTF-8">
    <title>Quiz</title>
    <link rel="stylesheet" type="text/css" href="style.css">
</head>
<body>
    <div class="grid">
        <div id="quiz">
            <h1>Quiz in JavaScript  Webdevtrick.com</h1>
            <hr style="margin-bottom: 20px">
 
            <p id="question"></p>
 
            <div class="buttons">
                <button id="btn0"><span id="choice0"></span></button>
                <button id="btn1"><span id="choice1"></span></button>
                <button id="btn2"><span id="choice2"></span></button>
                <button id="btn3"><span id="choice3"></span></button>
            </div>
 
            <hr style="margin-top: 50px">
            <footer>
                <p id="progress">Question x of y</p>
            </footer>
        </div>
    </div>
 
 
<script src="question.js"></script>
 
</body>
</html>