var OnReadyAjax = null;

function GetXmlHttpObject( handler )
{ 
  var objXMLHttp=null;
  
  if( window.XMLHttpRequest )
  {
    objXMLHttp = new XMLHttpRequest();
  }
  else if( window.ActiveXObject )
  {
    objXMLHttp = new ActiveXObject("Microsoft.XMLHTTP");
  }
  return objXMLHttp;
}

function ajaxStateChanged() 
{ 
  if( xmlHttp.readyState==4 || xmlHttp.readyState=="complete" )
  {
    OnReadyAjax( xmlHttp.responseText, true );
  } 
} 

function randomizeUrl( url )
{
  var date = new Date();
  return url + '&rand=' + date.getTime()
}

function ajaxSendString( str, url, on )
{  
  OnReadyAjax = on;
  OnReadyAjax('Chvíli strpení...', false);
  xmlHttp = GetXmlHttpObject();
    
  if( xmlHttp == null )
  {
    alert ("Váš prohlížeč nepodporuje AJAX, použijte prosím IE, Operu nebo Firefox nejnovější verze.");
    return;
  } 
  
  xmlHttp.onreadystatechange = ajaxStateChanged;
  
  xmlHttp.open( "POST", randomizeUrl(url), true ); 
  xmlHttp.setRequestHeader( "Content-Type", "application/x-www-form-urlencoded; charset=UTF-8" ); 
  xmlHttp.setRequestHeader( "Cache-Control", "no-cache, must-revalidate" );        
  xmlHttp.setRequestHeader( "If-Modified-Since", "Wed, 15 Nov 1995 04:58:08 GMT" );
  xmlHttp.setRequestHeader( "Pragma", "no-cache" );   

  xmlHttp.send( str );
}

function ajaxSaveCities( str, on )
{
  ajaxSendString( 'q=' + str, 'ajaxserver.php?action=save', on );
}

function ajaxGetCity( id, on )
{
  ajaxSendString( 'id=' + id, 'ajaxserver.php?action=getcity', on );
}

function ajaxUpdateCity( id, str, on )
{
  ajaxSendString( 'id=' + id + '&q=' + str, 'ajaxserver.php?action=updatecity', on );
}