controller:
 respond_to :js
...
 def make_favourite
    @card_image = CardImage.find(params[:id])
    @card_image.make_favourite!
    respond_with(@card_image)
  end

  def remove_favourite
    @card_image = CardImage.find(params[:id])
    @card_image.remove_favourite!
    respond_with(@card_image)
  end

view:
<span id="favourite_(some ID)">
link_to(label, send(make_favourite_path, :id => card_image.id), :remote => true)
</span>

make_favourite.js.erb
$(#favourite_<%= @card_image.id %>).html("test");

And i want that span tag to change to "test"
But I get a blank page after clicking the link