/* Otestovani delky hodnoty */
function isEmpty(el){
   var element = document.getElementById(el);
   if(element.value.length == 0){
      return false;
   }
   return true;
}
/* Otestovani delky hodnoty */
function isEmptyMsg(el,message){
   var element = document.getElementById(el);
   if(element.value.length == 0){
      alert(message);
      return false;
   }
   return true;
}
/* Vraci set vsech elementu daneho name v danem node */
function getElByName(node, name) {
	return node.getElementsByTagName(name);
}
/* Vraci text obsazeny v elementu s textovym obsahem */
function getContent(node) {
	return node.firstChild.data;
}
/* Zobrazeni boxu centrovane */
ViewPort = {
   centerObject : function(obj, width, height) {
      var viewportWidth, viewportHeight, scrollTop;
      if (self.innerHeight) {
         viewportWidth  = self.innerWidth;
         viewportHeight = self.innerHeight;
      } else if (document.documentElement && document.documentElement.clientHeight) {
         viewportWidth  = document.documentElement.clientWidth;
         viewportHeight = document.documentElement.clientHeight;
      } else if (document.body) {
         viewportWidth  = document.body.clientWidth;
         viewportHeight = document.body.clientHeight;
      }

      if (self.pageYOffset) {
         scrollTop = self.pageYOffset;
      } else if (document.documentElement && document.documentElement.scrollTop) {
         scrollTop = document.documentElement.scrollTop;
      } else if (document.body) {
         scrollTop = document.body.scrollTop;
      }

      obj.style.top  = parseInt(((viewportHeight - height) / 2) + parseInt(scrollTop)) + 'px';
      obj.style.left = parseInt((viewportWidth - width) / 2) + 'px';
   }
}
/*kontrola na datum*/
function isDate(el){
   var elem = document.getElementById(el);
   //var numericExpression = /^{2}[0-9]+\.{2}[0-9]+\.{2}[0-9]$/;
   var numericExpression = /[0-9]{1,2}\.+[0-9]{1,2}\.+[0-9]{4}$/;
   if(elem.value.match(numericExpression)){
      return true;
   }
   else{
      return false;
   }
}
/* odstrani polozky elementu */
function removeElement(elementSelect){
   var result = document.getElementById(elementSelect);
   while(result.childNodes.length > 0){
      result.removeChild(result.childNodes[0]);
   }
}