Adding a Quiz Timer, Fade Out/Skip to the next if timer reaches 0

Question

I'm really new to jQuery but familiar with some other languages. I recently bought a quiz type script and I'm trying to add a simple 15 second timer to each question. It's only a fun quiz, so no need to worry about users playing with the javascript to increase time etc.

Basically, if a user does not pick a question within 15 seconds, it will automatically go on to the next question and the timer starts over again.

Answers have the .next tag, and when chosen it moves onto the next question as the code below shows (hopefully).

superContainer.find('.next').click(function () {

            $(this).parents('.slide-container').fadeOut(500, function () {
                $(this).next().fadeIn(500)
            });

            return false
});

The problem i have is if i use setInterval, i don't know how i can select the appropriate div again for fade it our and fade in the next one. I've tried the below code and a few similar scrappy idea's but it doesn't work, but maybe it will give a better idea of what I'm after though.

superContainer.find('.next').click(function () {

    $active_count = $count;

    countInterval = setInterval(function() {
                $active_count--;
                if($active_count <= 0){
                    clearInterval(countInterval);
                    $active_count = $count;
                    $(this).parents('.slide-container').fadeOut(500, function () {
                        $(this).next().fadeIn(500)
                    });
                }
                $('.question-timer').html($active_count);
            }, 1000);

            $(this).parents('.slide-container').fadeOut(500, function () {
                $(this).next().fadeIn(500)
            });

            return false
});

I've only been using JQuery a day or two so excuse any obvious mistakes and bad code! Let me know if you need any other code or information

Answer 1

This is moderately tricky for a first jQuery project.

The knack (in this solution) is to factor out a goNext function that can be called in two ways - in response to a click event and in response to a 15 second setTimeout(), not setInterval().

$(function(){
    var questionTimeout = null;

    function goNext($el) {
        clearTimeout(questionTimeout);
        var $next = $el.next();
        $el.fadeOut(500, function() {
            if($next.length > 0) {
                $next.fadeIn(500, function() {
                    questionTimeout = setTimeout(function() {
                        goNext($next);
                    }, 15000);
                });
            }
            else {
                afterLastQuestion();
            }
        });
    }
    function afterLastQuestion(){
        alert("last question complete");
        $start.show();
    }

    var $superContainer = $("#superContainer").on('click', '.next', function() {
        goNext($(this).closest('.slide-container'));
        return false;
    });

    var $start = $("#start").on('click', function(){
        $(this).hide();
        $superContainer.find(".slide-container")
            .eq(0).clone(true,true)
            .prependTo(superContainer)
            .find(".next").trigger('click');
        return false;
    });
});

DEMO

The process is started by clicking a "start" link, causing the first question to be cloned followed by a simulated click on the clone's "next" link. This ensures that the (actual) first question is treated in exactly the same way as all the others.

I also included a afterLastQuestion() function. Modify its action to do whatever is necessary after the last question is answered (or times out).