left/right arrow keys on photo show page go to prev/next

app/helpers/photos_helper.rb

@@ -4,11 +4,11 @@ module PhotosHelper
     link_to (image_tag photo.url(:scaled_full)), photo_path(album.next_photo(photo)), :rel => "prefetch"
   end
 
-  def link_to_prev(photo, album)
-    link_to "<< prev", photo_path(album.prev_photo(photo)), :rel => "prefetch"
+  def url_to_prev(photo, album)
+    photo_path(album.prev_photo(photo))
   end
 
-  def link_to_next(photo, album)
-    link_to "next >>", photo_path(album.next_photo(photo)), :rel => "prefetch"
+  def url_to_next(photo, album)
+    photo_path(album.next_photo(photo))
   end
 end

app/views/photos/show.html.haml

+:javascript
+  $(document).keydown(function(e){
+    switch(e.keyCode) {
+    case 37:
+      window.location.replace( "#{url_to_prev(@photo,@album)}" );
+      break;
+    case 39:
+      window.location.replace( "#{url_to_next(@photo,@album)}" );
+      break;
+    }
+  });
+
+
 .back= link_to "⇧ #{@album.name}", album_path(@album)
 %h1.big_text
   = @photo.image
@@ -6,11 +19,11 @@
     = link_to 'Edit Photo', edit_photo_path(@photo), :class => "button"
 
 .sub_header
-  = link_to_prev @photo, @album
+  = link_to "<< prev", url_to_prev(@photo, @album)
   |
   = link_to "full size", @photo.url
   |
-  = link_to_next @photo, @album
+  = link_to "next >>", url_to_next(@photo, @album)
 
 %div{:id => @photo.id}
   #show_photo