/**
 * Cookie schreiben
 *
 * schreibt ein Cookie mit Expiretime oder Sessioncookie
 *
 * @param string name Cookiename
 * @param string value Cookiewert, -inhalt
 * @param string hours optional Expiretime in Stunden
 */
function writeCookie(name, value, hours) {
  var expire = "";
  if(hours != null) {
    expire = new Date((new Date()).getTime() + hours * 3600000);
    expire = "; expires=" + expire.toGMTString();
  }
  document.cookie = name + "=" + escape(value) + expire;
}
/**
 * Cookie lesen
 *
 * liest ein Cookiewert, -inhalt aus
 *
 * @param string name Cookiename
 * @return string cookieValue Cookiewert, -inhalt
 */
function readCookie(name) {
  var cookieValue = "";
  var search = name + "=";
  if(document.cookie.length > 0) {
    offset = document.cookie.indexOf(search);
    if (offset != -1) {
      offset += search.length;
      end = document.cookie.indexOf(";", offset);
      if (end == -1) end = document.cookie.length;
      cookieValue = unescape(document.cookie.substring(offset, end))
    }
  }
  return cookieValue;
}
/**
 * Trackinginformation schreiben
 *
 * übergibt den Trackingcode an ein Script, das als Bild (Image-Object) geladen wird.
 *
 * @param string trackerFile Dateiname des Trackingscripts
 * @param string trackerFile Trackingwert
 */
function track_user(trackerFile,trackerVal) {
	var trackerImageObj;
	var trackerImageSrc;

	trackerImageSrc	= trackerFile+"?trackerVal="+trackerVal;

	trackerImageObj = new Image();
	trackerImageObj.src = trackerImageSrc;
}
/**
 * Trackinginformation auslesen und schreiben wenn kein Cookie gelesen werden kann
 */
if(readCookie('trackUser') != 'false') {
	var color_depth = window.screen.colorDepth + 'bit';
	var screen_dim = window.screen.width + 'x' + window.screen.height;

	track_user("http://www.jvm-neckar.de/tracker/screen.gif", 	screen_dim);
	track_user("http://www.jvm-neckar.de/tracker/color.gif", 	color_depth);
}

writeCookie('trackUser', 'false', 24*30);