var t;
var menuon='uroven2menu1';
var menux=0;

var ie4=document.all && !document.getElementById;
if(ie4) {
    document.getElementById = new Function('var expr = /^\\w[\\w\\d]*$/, elname=arguments[0]; if(!expr.test(elname)) { return null; } else if(eval("document.all."+elname)) { return eval("document.all."+elname); } else return null;')
}


function schovej (idmenu) {
    if (document.getElementById) {
        document.getElementById(idmenu).style.visibility = 'hidden';
    }
    else
        alert ('Vá prohlíeč nepodporuje tuto funkci');
}
function ukaz (menu) {
    schovej (menuon);
		menuon = menu;
		menumezi = (menu+'mezi');
    if (document.getElementById) {
        document.getElementById (menu).style.visibility = 'visible';
		 				if (document.getElementById ('zakladna').offsetTop + 3 + document.getElementById (menu).offsetHeight - document.body.scrollTop > document.body.clientHeight) {
						document.getElementById (menu).style.top = document.body.clientHeight - document.getElementById ('zakladna').offsetTop - 3 - document.getElementById (menu).offsetHeight + document.body.scrollTop;
		 				}
			}
    else
        alert ('Vá prohlíeč nepodporuje tuto funkci');
}
function checkNEmail(form) {
	if (isBlank(form.email.value) || isBlank(form.name.value) || !isEmailValid(form.email.value) ) 
	{
		alert("Please enter a valid Name and  Email Address .\nThe email or name you have typed in does not appear to be valid.");
		form.email.focus();
		return false;
	}
	}

function checkEmail(form) {
	if (isBlank(form.email.value) || !isEmailValid(form.email.value) ) {
		alert("Please enter a valid Email Address.\nThe email you have typed in does not appear to be valid.");
		form.email.focus();
		return false;
	}
return true;

}

function isBlank(fieldValue) {
	var blankSpaces = / /g;
	fieldValue = fieldValue.replace(blankSpaces, "");
	return (fieldValue == "") ? true : false;
}

function isEmailValid(fieldValue) {
	var emailFilter = /^.+@.+\..{2,4}$/;
	var atSignFound = 0;
	for (var i = 0; i <= fieldValue.length; i++)
		if ( fieldValue.charAt(i) == "@" )
			atSignFound++;
	if ( atSignFound > 1 )
		return false;
	else
		return ( emailFilter.test(fieldValue) && !doesEmailHaveInvalidChar(fieldValue) ) ? true : false;
}

function doesEmailHaveInvalidChar(fieldValue) {
	var illegalChars = /[\(\)\<\>\,\;\:\\\/\"\[\] ]/;
	return ( illegalChars.test(fieldValue) ) ? true : false;
}