David Kimura PRO said over 3 years ago on Nested Comments from Scratch :
  Since the edit link_to  isn't a remote: true, you would be rendering a new view. You might be able to render the comment form within there. If you want it to be a bit more of an SPA feel, you could use the remote: true and then that would render the edit.js.erb where you can then render the form partial and display a modal.

If you want to make it load a new page to edit the comment, then you would need to render the form.