var emptyValue = '';
function checkValue(obj) {
  if (isNaN(obj.value) == true) {
    obj.value = emptyValue;
    alert("Just numbers, please!");
  }else {

      if (obj.value >= 5 && $("test").style.display=="none") {
          new Effect.Appear("test");
      } else if (obj.value <5 && $("test").style.display!="none"){
      new Effect.Fade("test");
      }
  }
}


function changeBgImage(bgImage) {
  //alert('farbe');
  document.getElementById("stepCounter").style.backgroundImage = 'url(\''+bgImage+'\')';
}