jQuery(document).ready(function() { 
	jQuery(".img-swap").hover(
          function(){this.src = this.src.replace("_off","_on");},
          function(){this.src = this.src.replace("_on","_off");
     });
	 jQuery(".img-swap-1").hover(
          function(){this.src = this.src.replace("_off","_on");},
          function(){this.src = this.src.replace("_on","_off");
     });
	 var imgSwap = [];
	 jQuery(".img-swap").each(function(){
		imgUrl = this.src.replace("_off","_on");
		imgSwap.push(imgUrl);
	});
	jQuery(imgSwap).preload();
});
jQuery.fn.preload = function() {
    this.each(function(){
        jQuery('<img/>')[0].src = this;
    });
}