Javascript Sample (Move a image)

  var retleft = 0;
  var rettop  = 120;
  function mytimer(){
    var itemfld = $('fld');
    var retfld = Element.getDimensions(itemfld);
    var elements = $$('div.z');
    for(var i=0;i<elements.length;i++){
      if(elements[i].id=='Obj0'){
        retleft -= 5;
        rettop  += 5;
        if(retleft < 0){retleft = retfld.width;}
        if(rettop > retfld.height){rettop = 0;}
        elements[i].setStyle({'left': retleft + 'px', 'top': rettop + 'px'});
      }
    }
    setTimeout("mytimer()", 50);
  }
  Element.observe(window, "load", function() {
    setTimeout("mytimer()", 50);
  });