With any programming language, when you do some client or day job work, you need to deliver quality software. When you contribute to FLOSS projects, you have to follow some style guides specified for that project. Great help with all of that are linters and style checkers.

JavaScript world if full of those… Just try to search npm package with word 'lint'…

My choice

However, flycheck package for GNU Emacs supports some of the biggest names: gjslint, jshint, eslint as linters and jscs and standard/semistandard as style checkers. I use only eslint (best ES6 support) and jscs (great support for JSDoc).

Both can be installed using npm. I also install babel-eslint because almost all my projects use babel.

Both tools require configuration files in project directory in order to work correctly.


Install with npm:

$ npm install -g eslint babel-eslint

You can install modules without -g flag, but then you need to set $PATH in Emacs.

Create .eslintrc file in your project directory (or your $HOME directory) with following:

  "extends": "eslint:recommended",
  "parser": "babel-eslint",
  "rules": {
    "strict": 0


Again, install with npm:

$ npm install -g jscs

In order to create .jscsrc file, best way is to point to your existing JavaScript file and then jscs will offer you some presets based on your coding style.

$ jscs --auto-configure <directory with your files or single js file>

In my example case I got config under this paragraph using js file with 20 lines… Not really correct style for mine taste, so please use a good example JavaScript file when you do this.

  "preset": "airbnb",
  "requireSpacesInAnonymousFunctionExpression": null

You can take it from there and tweak it if needed.

I also like to check JSDoc documentation in JavaScript files. In order to do that add following to your .jscsrc file:

  "preset": "airbnb",
  "requireSpacesInAnonymousFunctionExpression": null,
  "maxErrors": -1,
  "esnext": true,
  "plugins": [
  "jsDoc": {
    "checkAnnotations": "jsdoc3",
    "checkParamExistence": true,
    "checkParamNames": true,
    "checkRedundantParams": true,
    "checkReturnTypes": true,
    "checkRedundantReturns": true,
    "requireReturnTypes": true,
    "checkTypes": "strictNativeCase",
    "enforceExistence": true,
    "requireHyphenBeforeDescription": true,
    "requireParamDescription": true,
    "requireReturnDescription": true

That 'maxErrors' is in order to ask for all errors, without limit.

GNU Emacs settings

Well, flycheck will use eslint and then stop with collecting errors and warnings. jscs is never called if eslint is present. In most modes flycheck will chain checkers, one after another, but not for JavaScript. In order to chain checkers, add following somewhere in init.el:

(with-eval-after-load 'flycheck
  ;; Run javascript-jscs to run after javascript-eslint.
  (flycheck-add-next-checker 'javascript-eslint '(t . javascript-jscs)))
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