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An ESLint shareable config for the idiomatic js coding style.

Ensure your source code adheres to the idiomatic js coding style by linting your code with ESLint. Hook ESLint into your editor and build pipeline for maximum effect.

📝 Note for upgrades from v2.x: this config no longer extends eslint:recommended. See Usage.

Idiomatic example:

const thing = 'Hello',
  another = 'World',
  total = count([ 1, 2, 3]);

function idiomatic( arg ) {
  let out = 'Bye';
  if ( !arg ) {
    out = thing;
  } else if ( arg === thing ) {
    out = another;
  return out;


npm install --save-dev eslint-config-idiomatic


  • use version ^3.0.0 for ESLint version ^3.x.x.
  • use version ^2.0.0 for ESLint version ^2.x.x.
  • use version ^1.0.0 for ESLint version ^1.x.x.


In your .eslintrc file:

  "extends": "idiomatic"

To use with ESLint's recommended ruleset:

  "extends": [

Note: eslint:recommended should be listed first.


You can easily override rules in your own .eslintrc config. For example, to use 4 space indents instead of 2:

  "extends": "idiomatic",
  "rules": {
    "indent": [2, 4]


eslint-config-idiomatic is ES6+ by default. To use ES5, extend idiomatic/es5 in your .eslintrc:

  "extends": "idiomatic/es5"

Slight differences

The rules enforces by this config may differ slightly from the idiomatic js styleguide. These are outlined below.

Strict Indent

This config restricts to 2 spaces soft indent and will error when indentation differs.

Single quotes

Idiomatic does not enforce a particular style for quotes, but recommends consistency across the project. This config enforces 'single' quotes, but to override to use "double" quotes in your project:

  "extends": "idiomatic",
  "rules": {
    "quotes": [2, "double"]

Warn on missing function names

Names on functions are recommended as they will show in stack traces, which aids debugging immensely. eslint-config-idiomatic will only issue a warning instead of an error when a function name is omitted, which is useful for anonymous functions.

// Good (named function):
function foo() {
  return 'bar';

// Anonymous function (will issue warning):
var foo = function() {
  return 'bar';

// ES6 arrow function preferred for Anonymous functions (no warn, requires ES6+):
let foo = () => 'bar';


Issues and PRs more than welcome. Please ensure you have tests for your PRs, and that npm test passes.