/**
 * Created by Jacek on 2016-01-11.
 */

document.addEventListener("DOMContentLoaded", function () {
	var allElements = document.querySelectorAll('li');
	var elements = document.querySelectorAll('li:not([data-direction])');

	for (var i = 0; i < elements.length; i++) {
		elements[i].dataset.direction = 'up';//opcja 1
		elements[i].setAttribute('data-direction', 'up');//opcja 2
	}

	for (var i = 0; i < allElements.length; i++) {
		if (i % 2 === 0) {
			allElements[i].style.backgroundColor = 'green';
		}
	}

	document.querySelector('ul li:nth-child(5)').classList.add('big');
	///
	var nthChild = document.querySelectorAll('ul li:nth-child(3n)');

	for (var i = 0; i < nthChild.length; i++) {
		nthChild[i].style.textDecoration = 'underline';
	}
////////

	var optionElements = document.querySelectorAll('option');

	for (var i = 0; i < optionElements.length; i++) {
		var val = optionElements[i].getAttribute('value');
		optionElements[i].innerText = val;


		optionElements[i].dataset.year = parseInt(val) + 20;
	}

});