eslint-config-metalab

Lint JavaScript MetaLab style.

Overview

Just a little package for the JavaScript style guidelines used at MetaLab. Largely inspired by the rules and guidelines from AirBnB, but a little bit more opinionated.

Usage

npm install --save-dev eslint eslint-config-metalab

Just add the following to your .eslintrc:

{
  "extends": [
    "metalab",
    "metalab/react"
  ]
}

And run:

#!/bin/sh

# Use .gitignore as a base for .eslintignore
cp .gitignore .eslintignore

# Start linting
eslint .

You should add a lint command to your package so its easy to run. In your package.json you can add:

{
  "scripts": {
    "lint": "eslint ."
  }
}

and users can then lint your project easily with:

#!/bin/sh
npm run lint

It's recommended you use some combination of the rule packages:

Language Presets

• legacy - Old ES5/non-babel code.
• base - If you're using ES6/modern code.

Framework Presets

• react - If you're using code with the react framework.

If you need more fine-grained control you can import things in the rules/ directory.

Migrating

So you've set everything up but you're getting hundreds of errors because your project followed some other conventions or you've just upgraded rules. Don't fret! You can:

• Disable noisy rules or rules you don't like.
• Get eslint to automatically fix simple errors.
• Setup your CI to incrementally validate.

Disable Noisy Rules

You can disable the noisiest rules by simply temporarily blacklisting them:

{
  "extends": [
    "metalab",
    "metalab/react"
  ],
  "rules": {
    "noisy-rule": 0
  }
}

NOTE: The plugins this package uses are namespaced under metalab/. So for example, the rule import/no-commonjs becomes metalab/import/no-commonjs. This prevents users from having to install 10 different eslint plugins as dependencies and avoids all the peerDependency warnings that can happen when versions get bumped. This means if you want to disable a rule you need to disable the metalab/ prefixed version.

Automatic Fixing

You can get eslint to fix whole classes of errors with its builtin --fix command. Note that this won't fix everything and sometimes doesn't do exactly what you want, but it's still a handy tool to have at your disposal.

If you have eslint running via npm you can just amend your lint command:

#!/bin/sh
npm run lint -- --fix

Or you can run it manually:

#!/bin/sh
eslint --fix .

Gradual Migration

You can also setup lint checks to only lint files that have been modified on a particular branch, allowing you to bring changes up to spec gradually. First create a new .eslintrc.next file containing the new rules you wish to use and then run:

# Fetch the names of all the files that have been changed,
# Filter the list to only have JS files,
# Lint each of those files with the new config.
git --no-pager diff --name-only FETCH_HEAD $(git merge-base FETCH_HEAD master) \
  | egrep '\.js$' \
  | xargs ./node_modules/.bin/eslint -c .eslintrc.next

Clean up the low hanging fruit and progressively iterate to bring beauty and inner peace to your project. :gem: