Get Programming with JavaScript

Get Programming with JavaScript - Listing 12.07

Listing 12.07 - Checking quiz answers

var getQuiz = function () {
    var score = 0,
        qIndex = 0,
        inPlay = true,
        questions,
        next,
        getQuestion,
        checkAnswer,
        submit;

    questions = [
        {
            question: "What is the highest mountain in the world?",
            answer: "Everest"
        },
        {
            question: "What is the highest mountain in Scotland?",
            answer: "Ben Nevis"
        }
    ];

    next = function () {
        qIndex = qIndex + 1;

        if (qIndex >= questions.length) {
            inPlay = false;
            console.log("You have finished the quiz.");
        }
    };

    getQuestion = function () {
        if (inPlay) {
            return questions[qIndex].question;
        } else {
            return "You have finished the quiz.";
        }
    };

    checkAnswer = function (userAnswer) {
        if (userAnswer === questions[qIndex].answer) {
            console.log("Correct!");
            score = score + 1;
        } else {
            console.log("No, the answer is " + questions[qIndex].answer);
        }
    };

    submit = function (userAnswer) {
        var message = "You have finished the quiz.";

        if (inPlay) {
            checkAnswer(userAnswer);
            next();
            message = "Your score is " + score + " out of " + qIndex;
        }

        return message;
    };

    return {
        quizMe: getQuestion,
        submit: submit
    };
};

var quiz = getQuiz();

Further Adventures

Listing 12.07 - Checking quiz answers - Task 4

Add a hint property for each question.

var getQuiz = function () {
    var score = 0,
        qIndex = 0,
        inPlay = true,
        questions,
        next,
        getQuestion,
        checkAnswer,
        submit;

    questions = [
        {
            question: "What is the highest mountain in the world?",
            answer: "Everest",
            hint: "It's been the tallest, like, forever!"
        },
        {
            question: "What is the highest mountain in Scotland?",
            answer: "Ben Nevis",
            hint: "It's not Ben Franklin!"
        }
    ];

    next = function () {
        qIndex = qIndex + 1;

        if (qIndex >= questions.length) {
            inPlay = false;
            console.log("You have finished the quiz.");
        }
    };

    getQuestion = function () {
        if (inPlay) {
            return questions[qIndex].question;
        } else {
            return "You have finished the quiz.";
        }
    };

    checkAnswer = function (userAnswer) {
        if (userAnswer === questions[qIndex].answer) {
            console.log("Correct!");
            score = score + 1;
        } else {
            console.log("No, the answer is " + questions[qIndex].answer);
        }
    };

    submit = function (userAnswer) {
        var message = "You have finished the quiz.";

        if (inPlay) {
            checkAnswer(userAnswer);
            next();
            message = "Your score is " + score + " out of " + qIndex;
        }

        return message;
    };

    return {
        quizMe: getQuestion,
        submit: submit
    };
};

var quiz = getQuiz();

Listing 12.07 - Checking quiz answers - Tasks 5 & 6

Define a getHint function that returns the hint for the current question.
Add a helpMe property to the public interface, the object returned by getQuiz.
The getHint function should be assigned to the helpMe property.

var getQuiz = function () {
    var score = 0,
        qIndex = 0,
        inPlay = true,
        questions,
        next,
        getQuestion,
        getHint,   // declare a variable
        checkAnswer,
        submit;

    questions = [
        {
            question: "What is the highest mountain in the world?",
            answer: "Everest",
            hint: "It's been the tallest, like, forever!"
        },
        {
            question: "What is the highest mountain in Scotland?",
            answer: "Ben Nevis",
            hint: "It's not Ben Franklin!"
        }
    ];

    next = function () {
        qIndex = qIndex + 1;

        if (qIndex >= questions.length) {
            inPlay = false;
            console.log("You have finished the quiz.");
        }
    };

    getQuestion = function () {
        if (inPlay) {
            return questions[qIndex].question;
        } else {
            return "You have finished the quiz.";
        }
    };

    getHint = function () {
        if (inPlay) {
            return questions[qIndex].hint;
        }

        return "You have finished the quiz.";
    };

    checkAnswer = function (userAnswer) {
        if (userAnswer === questions[qIndex].answer) {
            console.log("Correct!");
            score = score + 1;
        } else {
            console.log("No, the answer is " + questions[qIndex].answer);
        }
    };

    submit = function (userAnswer) {
        var message = "You have finished the quiz.";

        if (inPlay) {
            checkAnswer(userAnswer);
            next();
            message = "Your score is " + score + " out of " + qIndex;
        }

        return message;
    };

    return {
        quizMe: getQuestion,
        helpMe: getHint,
        submit: submit
    };
};

var quiz = getQuiz();

Notice how getHint doesn't use an else-clause. Because the if-block returns a value, ending the function, the second return statement will only be reached if inPlay is false.

Have a go at removing the else-clause from the getQuestion function.