// JavaScript Document

(function() {
  function attach(obj, eventName, handler, capcha) {
    if (obj.addEventListener){
      obj.addEventListener(eventName, handler, capcha);
    } else if (obj.attachEvent){
      obj.attachEvent('on'+eventName, function () { handler.call(event.srcElement);});
    }
  }

  function getRolloverSrc(src) {
    var i = src.lastIndexOf('.');
    var basename = src.substring(0,i);
    var ext = src.substring(i,src.length);
    return basename+'_ro'+ext;
  }

  function initRollOver() {
    var caches = [];
    var elems = document.getElementsByTagName("img");
    for (var i = 0; i < elems.length; i++) {
      var elem = elems[i];
      var className = elem.getAttribute('class') || elem.getAttribute('className');
      if (className && className.indexOf('rollover') != -1) {

        // Attache event handler.
        attach(elem, 'mouseover', function() {
          this.setAttribute('src', getRolloverSrc(this.getAttribute('src')));
        }, false);
        attach(elem, 'mouseout', function() {
          this.setAttribute('src', this.getAttribute('src').replace('_ro.', '.'));
        }, false);

        // Preload images.
        var img = new Image();
        img.src = getRolloverSrc(elem.getAttribute('src'));
        caches.push(img);
      }
    }
  }

  attach(window, 'load', initRollOver, false);
})();