Question

For example, in the codes of zen-coding, the “C-j” shadows the normal behavior of “C-j” (newline-and-indent)

(define-key zencoding-mode-keymap (kbd "C-j") 'zencoding-expand-line)

Then how can I unset this keybinding and use C-j for newline-and-indent again?

I tried this, but it doesn’t work:

(add-hook 'html-mode-hook
          (lambda ()
            (progn
              (zencoding-mode)
              (local-set-key (kbd "C-j") 'newline-and-indent))))

Does anyone have ideas about this?

Answer 1

The general way to unbind a key (for any keymap) is to define a binding of nil:

(define-key KEYMAP KEY nil)

For convenience, there are also two standard functions for unbinding from the global keymap and from the local keymap (which is usually the major mode’s keymap).

• (global-unset-key KEY)
• (local-unset-key KEY)

Those ones are interactive commands, as per their respective complements global-set-key and local-set-key.

As to your specific example, you probably want something like this:

(with-eval-after-load "zencoding-mode"
  (define-key zencoding-mode-keymap (kbd "C-j") nil))

---

For the benefit of other readers trying to do similar things, those arguments are "zencoding-mode" because the library being loaded is named zencoding-mode.el (note that you should omit the ".el" suffix); and zencoding-mode-keymap rather than the typical/expected zencoding-mode-map because zencoding-mode.el is unusual in explicitly declaring its keymap and not using the standard name for it.

Use C-hk to check what the key in question is bound to, and Emacs will tell you both the name of the keymap and the name of the library, which establishes both arguments.