var first = 1;
var last = "";
var nbItems = "";

function getNbMonth() {
	nbItems = document.getElementsByClassName("ok").length + document.getElementsByClassName("nok").length;
}

function getLast() {
	last = document.getElementsByClassName("ok").length;
}

function goup() {
	if (last == "") getLast();
	if (nbItems == "") getNbMonth();

	if (last != nbItems) {
		document.getElementById(first).style.display = "none";
		first = first + 1;
		document.getElementById(last + 1).style.display = "block";
		last = last + 1;
		document.getElementById("up").src = "/wp-content/plugins/prettyjsarchives/images/haut_bleu.png";
		if (last == nbItems) {
			document.getElementById("down").src = "/wp-content/plugins/prettyjsarchives/images/bas_gris.png";
		}
	}
}

function godown() {
	if (last == "") getLast();
	if (nbItems == "") getNbMonth();

	if (first != 1) {
		document.getElementById(first-1).style.display = "block";
		first = first-1;
		document.getElementById(last).style.display = "none";
		last = last-1;
		document.getElementById("down").src = "/wp-content/plugins/prettyjsarchives/images/bas_bleu.png";
		if (first == 1) {
			document.getElementById("up").src = "/wp-content/plugins/prettyjsarchives/images/haut_gris.png";
		}
	}
}