bug#21568: [PATCH] Add prettify-symbols-alist for js-mode

[Simen Heggestøyl]

With the introduction of the fat arrow (=>) function notation in

ECMAScript 6, why not make them prettier by default when

prettify-symbols-mode is turned on?

I propose the following patch, which also adds pretty versions of >=

and <= while we're at it:

From fa37953359f50748801717d259350d7e352cff60 Mon Sep 17 00:00:00 2001

From: =?UTF-8?q?Simen=20Heggest=C3=B8yl?= <simenheg@gmail.com>

Date: Wed, 23 Sep 2015 21:49:24 +0200

Subject: [PATCH] Add prettify-symbols-alist for js-mode

* lisp/progmodes/js.el (js--prettify-symbols-alist): New defconst.

(js-mode): Use it.

---

 lisp/progmodes/js.el | 7 +++++++

 1 file changed, 7 insertions(+)

diff --git a/lisp/progmodes/js.el b/lisp/progmodes/js.el

index 6a800f8..f214015 100644

--- a/lisp/progmodes/js.el

+++ b/lisp/progmodes/js.el

@@ -1724,6 +1724,12 @@ This performs fontification according to `js--class-styles'."

            (js-syntax-propertize-regexp end))))))

    (point) end))

 

+(defconst js--prettify-symbols-alist

+  '(("=>" . ?⇒)

+    (">=" . ?≥)

+    ("<=" . ?≤))

+  "Alist of symbol prettifications for _javascript_.")

+

 ;;; Indentation

 

 (defconst js--possibly-braceless-keyword-re

@@ -3495,6 +3501,7 @@ If one hasn't been set, or if it's stale, prompt for a new one."

   (setq-local open-paren-in-column-0-is-defun-start nil)

   (setq-local font-lock-defaults (list js--font-lock-keywords))

   (setq-local syntax-propertize-function #'js-syntax-propertize)

+  (setq-local prettify-symbols-alist js--prettify-symbols-alist)

 

   (setq-local parse-sexp-ignore-comments t)

   (setq-local parse-sexp-lookup-properties t)

-- 

2.5.1