function validatePoll()
{
	//if poll question is "option type" user has to choose one answer.
	requiredFields = getElementsByClassName("required");
	
	if ( ( document.getElementById('questionType').value == "OPTION" ) || 
		( document.getElementById('questionType').value == "CHECKBOX" ) ) {
		for (var i=0;i<requiredFields.length;i++){
			if ( requiredFields[i].checked == true ){
				return true;
				}
		}
		return false;
	} else if ( document.getElementById('questionType').value == "TEXTAREA" ){
		var notAnswered = 0;
		var answer = true;
		for (var i=0;i<requiredFields.length;i++){
			if ( trim( requiredFields[i].value ) == "" ){
				notAnswered++;
				}
		}
		if ( notAnswered == requiredFields.length ){
			answer = confirm("Opravdu nechcete na tuto otázku odpovědět?");
		} else if (notAnswered > 0 ){
			answer = confirm("Opravdu nechcete odpovědět na všechny části otázky?");
		}
		return answer;
	}
}
/**
 * checks if required fields are not empty
 * all required fields have to be in class named required
 * if the field has specified title than show title in alert - title should 
 * be in format Insert your name. Insert your address. Etc.
 */
function validateForm ()
{
	requiredFields = getElementsByClassName("required");
	
	for (var i=0;i<requiredFields.length;i++)
	{
		if ( trim (requiredFields[i].value) == "" ){
			if (requiredFields[i].title){
				alert (requiredFields[i].title);
			}
			else{
				alert ("Je třeba vyplnit všechny povinné položky!");
			}
			requiredFields[i].focus();
			return false;
		}
	}
	return true;
}


/**
* get all element with defined class name
* @param string className name of class we are looking for
* @return array all elements with defined class
*/
function getElementsByClassName(className) 
{ 
	var arr = new Array(); 
	var elements = document.getElementsByTagName("*");
	for ( var cls, i = 0; ( element = elements[i] ); i++ )
	{
		if ( element.className.indexOf(className) != -1 )
		{
			arr[arr.length] = element;
		}
	}
	return arr;
}

/**
 * trim function
 */
function trim(str)
{
   return str.replace(/^\s*|\s*$/g,"");
}