version = navigator.appVersion.toLowerCase();
agent = navigator.userAgent.toLowerCase();
ie = (version.indexOf('msie')>-1);
win = (version.indexOf('windows')>-1);
opera = (agent.indexOf('opera')>-1);
ie50 = (version.indexOf('msie 5.0')>-1);

function prn() {
	document.write(' \074span class\=\"separator\"\076\&bull\;\074/span\076 \074a href=\"javascript:goprn();\"\076vytisknout stránku\074/a\076');
}

function goprn() {
	window.print();
}

function fav() {
	if ((opera) && (win)) return false;
	else if ((ie) && (win)) document.write(' \074span class\=\"separator\"\076\&bull\;\074/span\076 \074a href=\"javascript:gofav();\"\076přidat web do záložek\074/a\076');
}

function gofav() {
	window.external.addFavorite('http://www.portal.cz','Portál - knihy pro celou rodinu');
}

function trimChars(mystring, validchars) {
	var i;
	var returnstring = "";

	for (i = 0; i < mystring.length; i++)	{
		var c = mystring.charAt(i);
		if (validchars.indexOf(c) == -1) returnstring += c;
	}
	return returnstring;
}

// osetreni spousteni vice skriptu behem onload
function addLoadEvent(func) {
	var oldonload = window.onload;
	if (typeof window.onload != 'function') {
		window.onload = func;
	} else {
		window.onload = function() {
			if (oldonload) {
				oldonload();
			}
			func();
		}
	}
}