if (document.images) {
  bulletOn = new Image();
  bulletOn.src = "al/bullet1.gif";
  bulletOff = new Image();
  bulletOff.src = "al/bullet0.gif";
 
function swapImages() {
        for (var i=0; i<swapImages.arguments.length;i+=2){
         document[swapImages.arguments[i]].src = eval(swapImages.arguments[i+1] + ".src");
             }
         }
}