gistfile1.js

(function() {
	
	var showIndex = 0;
	var titles = document.querySelectorAll('.kysymys');
	var questions = document.querySelectorAll('.kysymys + p');
	var submit = document.querySelectorAll('button[type="submit"]')[0];

	function hideElement (element) {
		if (!element) {
			return;	
		}
		element.style.display = 'none';
	}

	function showElement (element) {
		if (!element) {
			return;	
		}
		element.style.display = '';
	}

	hideElement(submit);

	for (var i = 0; i < titles.length; i++) {
		if (i != showIndex)
			hideElement(titles[i]);
	}

	for (var i = 0; i < questions.length; i++) {
		if (i != showIndex)
			hideElement(questions[i]);

		questions[i].addEventListener('click', function (event) {
			if (!event.target && event.target.nodeName !== 'INPUT') {
				return;
			}

			if (event.target.parentElement !== questions[showIndex]) {
				return;
			}

			showIndex++;
			if (showIndex === titles.length) {
				showElement(submit);
			} else {
				showElement(titles[showIndex]);
				showElement(questions[showIndex]);
			}
		});
	}
})();