function getWindowWidth() {
  var windowWidth;
  if (navigator.appName == "Microsoft Internet Explorer") {
    windowWidth = document.body.clientWidth;
  }
  else {
    windowWidth = window.innerWidth;
  }
  return windowWidth;
}

function controlImage(id) {
  var elem = document.getElementById(id);
  var width = getWindowWidth();
  if(getWindowWidth() < 900) {
    elem.src = "/src/nadeln_sehrklein.gif";
  }
  else if(getWindowWidth() < 1100) {
    elem.src = "/src/nadeln_klein.gif";
  }
  else if(getWindowWidth() < 1350) {
    elem.src = "/src/nadeln.gif";
  }
  else {
    elem.src = "/src/nadeln_gross.gif";
  }
  window.setTimeout("controlImage('" + id + "')", 500);
}

window.onload = function() { controlImage("logo1"); }