var buy1_off = new Image();
buy1_off.src = "images/buy_off.gif";
var buy1_on = new Image();
buy1_on.src = "images/buy_on.png";

var buy2_off = new Image();
buy2_off.src = "images/buy_off.gif";
var buy2_on = new Image();
buy2_on.src = "images/buy_on.png";

var buy3_off = new Image();
buy3_off.src = "images/buy_off.gif";
var buy3_on = new Image();
buy3_on.src = "images/buy_on.png";

var buy4_off = new Image();
buy4_off.src = "images/buy_off.gif";
var buy4_on = new Image();
buy4_on.src = "images/buy_on.png";

var buy5_off = new Image();
buy5_off.src = "images/buy_off.gif";
var buy5_on = new Image();
buy5_on.src = "images/buy_on.png";

var buy6_off = new Image();
buy6_off.src = "images/buy_off.gif";
var buy6_on = new Image();
buy6_on.src = "images/buy_on.png";


function activate(imgName) {
  if ( eval(imgName + "_on.complete") ) {
    document.images[imgName].src = eval(imgName + "_on.src");
  }
}

function deactivate(imgName) {
  if ( eval(imgName + "_off.complete") ) {
    document.images[imgName].src = eval(imgName + "_off.src");
  }
}