update-image-alt-from-src

<script>
 var imagesRef = document.getElementsByTagName('img'); 
  for(var i = 0; i < imagesRef.length; i++) {
		var filename = imagesRef[i].src;
		var oldAlt = imagesRef[i].alt;
		if(oldAlt != null){
			var newRa = filename.substring(0, filename.lastIndexOf('.'));
    		var imgObj = newRa.split("/");
			imagesRef[i].alt = imgObj.slice(-1);
		}
		 
	}
</script>