# babel-eslint [![Build Status][travis-image]][travis-url]

**babel-eslint** allows you to lint **ALL** valid Babel code with the fantastic
[ESLint](https://github.com/eslint/eslint).

`babel-eslint` is successfully linting [babel core](https://github.com/babel/babel/blob/master/.eslintrc) and many other projects.

> If there is an issue, first check if it can be reproduced with the regular parser or with the latest versions of `eslint` and `babel-eslint`!

For questions and support please visit the [`#linting`](https://babeljs.slack.com/messages/linting/) babel slack channel (sign up [here](https://babel-slack.herokuapp.com))!

## Known Issues
Flow:
- `no-undef` for global flow types: `ReactElement`, `ReactClass` [#130](https://github.com/babel/babel-eslint/issues/130#issuecomment-111215076)
  - Workaround: define types as globals in `.eslintrc` or define types and import them `import type ReactElement from './types'`
- `no-unused-vars/no-undef` with Flow declarations (`declare module A {}`) [#132](https://github.com/babel/babel-eslint/issues/132#issuecomment-112815926)

Modules/strict mode
- `no-unused-vars: [2, {vars: local}]` [#136](https://github.com/babel/babel-eslint/issues/136)

Please check out [eslint-plugin-react](https://github.com/yannickcr/eslint-plugin-react) for React/JSX issues
- `no-unused-vars` with jsx

Please check out [eslint-plugin-babel](https://github.com/babel/eslint-plugin-babel) for other issues such as:
- `generator-star` with async/await functions [#78](https://github.com/babel/babel-eslint/issues/78)
- `object-shorthand` with spread operator [#131](https://github.com/babel/babel-eslint/issues/131)

## How does it work?

ESLint allows custom parsers. This is great but some of the syntax nodes that Babel supports
aren't supported by ESLint. When using this plugin, ESLint is monkeypatched and your code is
transformed into code that ESLint can understand. All location info such as line numbers,
columns is also retained so you can track down errors with ease.

## Usage

### Install

```sh
$ npm install -g eslint babel-eslint
```

### Setup

**.eslintrc**

```json
{
  "parser": "babel-eslint",
  "rules": {
    "strict": 0
  }
}
```

Check out the [ESLint docs](http://eslint.org/docs/rules/) for all possible rules.

### Run

```sh
$ eslint your-files-here
```

[travis-url]: https://travis-ci.org/babel/babel-eslint
[travis-image]: https://travis-ci.org/babel/babel-eslint.svg?branch=master