How do I do live Markdown previewing as I'm writing it?

Question

How can I do that either in a different buffer or even in the current buffer?

I'm trying to do Github README.md and other Github rendering of Markdown (for notes and such),

Answer 1

Here's a pretty long but efficient solution.

1. Install simple-httpd and M-x httpd-start.
2. Install markdown from your system's package manager.
3. Open your markdown buffer and run markdown-export. That produces a HTML file in the same directory.
4. Open that HTML file.
5. Install impatient-mode and M-x impatient-mode.
6. Go back to your markdown file.

Finally, evaluate this code:

(defun markdown-export-continuous (&optional output-file)
  (interactive)
  (let ((input-file (buffer-file-name))
        (output-file (markdown-export-file-name ".html")))
    (when output-file
      (with-current-buffer (find-file-noselect output-file)
        (erase-buffer)
        (insert
         (shell-command-to-string
          (format "markdown %s" input-file)))
        (save-buffer)))))
(add-hook 'after-save-hook 'markdown-export-continuous t t)

Note that the add-hook statement needs to be local to Markdown, so run it in that buffer.

After all this, open your browser on http://localhost:8080/imp/ and it will refresh each time you C-x C-s.

Answer 2

As of markdown-mode 2.1, this is functionality is provided in markdown-live-preview-mode (bound to C-c C-c l).

It uses eww for rendering the HTML. Screenshot: