// z(ne)viditelneni prvku
function showElement(name1, name2) {
	var obj1 = document.getElementById(name1);
	var obj2 = document.getElementById(name2);
	obj1.style.display = 'block';
	obj2.style.display = 'none';

	setCookie('flat-selector', name1, '', '/');

	var obj3 = document.getElementById('set-flash');
	var obj4 = document.getElementById('set-table');

	if (name1=='flash') {
		obj3.className='sel-tab';
		obj4.className='tab-sel';
	} else {
		obj4.className='sel-tab';
		obj3.className='tab-sel';
	}
}

function setFlatSelector() {
	var flat_sel=getCookie('flat-selector');

	if (flat_sel==null) {
		showElement('flash', 'table');
	} else {
		if (flat_sel=="table") {
			showElement('table', 'flash');
		} else {
			showElement('flash', 'table');
		}
	}
}

function setCookie(name, value, expires, path, domain, secure) {
    document.cookie= name + "=" + escape(value) +
        ((expires) ? "; expires=" + expires.toGMTString() : "") +
        ((path) ? "; path=" + path : "") +
        ((domain) ? "; domain=" + domain : "") +
        ((secure) ? "; secure" : "");
}

function getCookie(name) {
    var dc = document.cookie;
    var prefix = name + "=";
    var begin = dc.indexOf("; " + prefix);
    if (begin == -1) {
        begin = dc.indexOf(prefix);
        if (begin != 0) return null;
    } else {
        begin += 2;
    }
    var end = document.cookie.indexOf(";", begin);
    if (end == -1) {
        end = dc.length;
    }
    return unescape(dc.substring(begin + prefix.length, end));
}

<!--
// 4. CS
function vypocet_cs () {
var splatnost
var uver
var urok
var pocet_splatek
var mocnina
var anuita

uver = document.getElementById('uver').value;
var delka_uveru=document.getElementById('delka_uveru');
var mesicni_splatka=document.getElementById('mesicni_splatka');

splatnost = delka_uveru.options[delka_uveru.options.selectedIndex].value
urok = 0.0339;

pocet_splatek = splatnost * 12;
mocnina = Math.pow(1+(urok/12),pocet_splatek);
anuita = (uver*(urok/12)*mocnina)/(mocnina-1)
anuita_round = Math.round(anuita);
mesicni_splatka.value = anuita_round;
}
<!-- konec skriptu -->