A JavaScript refactoring library for emacs
Emacs Lisp Cucumber Other
Latest commit 634c475 Sep 20, 2016 @NicolasPetton NicolasPetton committed on GitHub Merge pull request #74 from futurist/master
ADD: js2r-toggle-arrow-function-and-expression(key t a) and some helper functions


js2-refactor.el Build Status

A JavaScript refactoring library for emacs.

This is a collection of small refactoring functions to further the idea of a JavaScript IDE in Emacs that started with js2-mode.

Breaking change in 0.7.0

js2-refactor.el is now a minor mode that has to be enabled, with something like the following:

(add-hook 'js2-mode-hook #'js2-refactor-mode)

Breaking change in 0.6.0

You now choose your own keybinding scheme. If you just want what you had before this change, add this to your init:

(js2r-add-keybindings-with-prefix "C-c C-m")

See Setup keybindings below for more.


I highly recommend installing js2-refactor through elpa.

It's available on melpa:

M-x package-install js2-refactor

You can also install the dependencies on your own, and just dump js2-refactor in your path somewhere:

I also recommend that you get expand-region to more easily mark vars, method calls and functions for refactorings.

Then add this to your emacs settings:

(require 'js2-refactor)
(add-hook 'js2-mode-hook #'js2-refactor-mode)

Setup keybindings

All functions in js2-refactor have a two-letter mnemonic shortcut. For instance, extract-function is ef. You get to choose how those are bound. Here's how:

(js2r-add-keybindings-with-prefix "C-c C-m")
;; eg. extract function with `C-c C-m ef`.

If you would rather have a modifier key, instead of a prefix, do:

(js2r-add-keybindings-with-modifier "C-s-")
;; eg. extract function with `C-s-e C-s-f`.

If neither of these appeal to your sense of keyboard layout aesthetics, feel free to pick and choose your own keybindings with a smattering of:

(define-key js2-refactor-mode-map (kbd "C-c C-e C-f") 'js2r-extract-function)


  • ef is extract-function: Extracts the marked expressions out into a new named function.
  • em is extract-method: Extracts the marked expressions out into a new named method in an object literal.
  • ip is introduce-parameter: Changes the marked expression to a parameter in a local function.
  • lp is localize-parameter: Changes a parameter to a local var in a local function.
  • eo is expand-object: Converts a one line object literal to multiline.
  • co is contract-object: Converts a multiline object literal to one line.
  • eu is expand-function: Converts a one line function to multiline (expecting semicolons as statement delimiters).
  • cu is contract-function: Converts a multiline function to one line (expecting semicolons as statement delimiters).
  • ea is expand-array: Converts a one line array to multiline.
  • ca is contract-array: Converts a multiline array to one line.
  • wi is wrap-buffer-in-iife: Wraps the entire buffer in an immediately invoked function expression
  • ig is inject-global-in-iife: Creates a shortcut for a marked global by injecting it in the wrapping immediately invoked function expression
  • ag is add-to-globals-annotation: Creates a /*global */ annotation if it is missing, and adds the var at point to it.
  • ev is extract-var: Takes a marked expression and replaces it with a var.
  • iv is inline-var: Replaces all instances of a variable with its initial value.
  • rv is rename-var: Renames the variable on point and all occurrences in its lexical scope.
  • vt is var-to-this: Changes local var a to be this.a instead.
  • ao is arguments-to-object: Replaces arguments to a function call with an object literal of named arguments.
  • 3i is ternary-to-if: Converts ternary operator to if-statement.
  • sv is split-var-declaration: Splits a var with multiple vars declared, into several var statements.
  • ss is split-string: Splits a string.
  • uw is unwrap: Replaces the parent statement with the selected region.
  • lt is log-this: Adds a console.log() statement for what is at point (or region).
  • dt is debug-this: Adds a debug() statement for what is at point (or region).
  • sl is forward-slurp: Moves the next statement into current function, if-statement, for-loop or while-loop.
  • ba is forward-barf: Moves the last child out of current function, if-statement, for-loop or while-loop.
  • k is kill: Kills to the end of the line, but does not cross semantic boundaries.

There are also some minor conveniences bundled:

  • C-S-down and C-S-up moves the current line up or down. If the line is an element in an object or array literal, it makes sure that the commas are still correctly placed.


A list of some wanted improvements for the current refactorings.

  • expand- and contract-array: should work recursively with nested object literals and nested arrays.
  • expand- and contract-function: should deal better with nested object literals, array declarations, and statements terminated only by EOLs (without semicolons).
  • wrap-buffer-in-iife: should skip comments and namespace initializations at buffer start.
  • extract-variable: could end with a query-replace of the expression in its scope.


  • Matt Briggs contributed js2r-add-to-globals-annotation
  • Alex Chamberlain contributed contracting and expanding arrays and functions.
  • Nicolas Petton contributed lots of stuff and is now a co-maintainer of the project.
  • Brian J Brennan added support for const and let to inline-var.



This project is still in its infancy, and everything isn't quite sorted out yet. If you're eager to contribute, please add an issue here on github and we can discuss your changes a little before diving into the elisp. :-)

To fetch the test dependencies, install cask if you haven't already, then:

$ cd /path/to/js2-refactor.el
$ cask

Run the tests with:

$ ./run-tests.sh


Copyright (C) 2012-2014 Magnar Sveen

Copyright (C) 2015-2016 Magnar Sveen and Nicolas Petton

Author: Magnar Sveen magnars@gmail.com, Nicolas Petton nicolas@petton.fr

Keywords: javascript refactorings

This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version.

This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.

You should have received a copy of the GNU General Public License along with this program. If not, see http://www.gnu.org/licenses/.