function isDate(p_dateField, p_restricted_valid) {

//    var datePat = /^(\d{1,2})(\/|-|.)(\d{1,2})(\/|-|.)(\d{4})$/;
    var datePat = /^(\d{1,2})(.)(\d{1,2})(.)(\d{4})$/;
    var matchArray = p_dateField.value.match(datePat); // is the format ok?
    var result = true;
    if (matchArray == null) {
        result = false;
    } else {
        month = matchArray[3]; 
        day = matchArray[1];
        year = matchArray[5];
            
        if (month < 1 || month > 12) { 
            result = false;
        }
    
        if (day < 1 || day > 31) {
            result = false;
        }
    
        if ((month==4 || month==6 || month==9 || month==11) && day==31) {
            result = false;
        }
    
        if (month == 2) { 
            var isleap = (year % 4 == 0 && (year % 100 != 0 || year % 400 == 0));
            if (day > 29 || (day==29 && !isleap)) {
                result = false;
            }
        }
    }
    if (!result && (p_dateField.value.length != 0)) {
        alert("Моля въведете датата в следния формат: дд.мм.гггг");
        p_dateField.value = '';
        if (p_restricted_valid){
            p_dateField.focus();
        }
    }
    return result; 
}

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