function RETINAAAA()
{
var images = document.getElementsByClassName("retina");
for(var i = 0; i<images.length; i++)
{
    images[i].width = images[i].width;
    images[i].height = images[i].height;
    images[i].src = images[i].src.replace(/\.[a-z]+$/,'@2x$&');
}
}
document.onload = RETINAAAA;