substitute function(x) with f(x) in javascript-mode emacs

Question

I am new to emacs and emacs-lisp so i don't have any idea how to write extensions to emacs but i came accross awesome extensions like 'pretty-lambdas' which swaps

(lambda (x) (+ x x)) ---->  (λ (x) (+ x x))

In emacs-lisp mode. I was able to make it work for clojure such that i get :

(fn [x] (+ x x)) ----->     (λ [x] (+ x x))

I would like to do the same for javascript, such that In javascript mode instead of

function(x){}

I get . f(x) {}

how do i achieve this? Thanks.

Community · Accepted Answer · 2017-05-23 12:30:53Z

6

I've never used pretty lambdas, but there are a number of other libraries that can do this.

In Emacs 24.4, there is a new built-in mode called prettify-symbols-mode. You should be able to do something like

(add-hook 'js-mode-hook
          (lambda ()
            (push '("function" . ?ƒ) prettify-symbols-alist)
            (prettify-symbols-mode)))

Thanks to Stefan, who points out in the comments that there is also global-prettify-symbols-mode, in case you want to enable this mode all the time.

Alternatively, you could use pretty-mode, pretty-symbols or purty-mode, all available in MELPA, and pretty-mode is also in MELPA stable.

Something like this should work for purty-mode:

(purty-add-pair '("\\(\\bfunction\\b\\)" . "ƒ"))
(add-hook 'js-mode-hook #'purty-mode)

Note that purty-mode only seems to have a single replacement table, so the function → ƒ replacement will affect all buffers where purty-mode is active.

edited May 23, 2017 at 12:30

CommunityBot

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answered Sep 8, 2014 at 21:51

Chris

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2 Comments

Mukiza Andrew Over a year ago

when I am editing javascript files my emacs shows, the mode as Javascript not js. So my purty-add-pair seems to not work. so I still don't have "function" . "ƒ" working. However, I like purty.

Stefan Over a year ago

Regarding prettify-symbols-mode, it is worth noting that there is also a global-prettify-symbols-mode you can activate once and for all in your ~/.emacs.

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