Neutrino preset for Eslint w/ Prettier configured to OMT Tech's conventions

@omt-tech/neutrino-eslint-prettier is a Neutrino preset that supports linting React projects with ESLint and Prettier configured to OMT conventions.

TODO!!! Replace neutrino-airbnb's README text below

Features

• Zero upfront configuration necessary to start linting your React project
• Modern Babel knowledge supporting ES modules, JSX, and more
• Highly visible during development, fails compilation when building for production
• Easily extensible to customize your project as needed

Requirements

• Node.js v6.10+
• Yarn or npm client
• Neutrino v8, Neutrino build preset

Installation

@neutrinojs/airbnb can be installed via the Yarn or npm clients. Inside your project, make sure neutrino and @neutrinojs/airbnb are development dependencies. You will also be using another Neutrino preset for building your application source code.

Yarn

❯ yarn add --dev @neutrinojs/airbnb

npm

❯ npm install --save-dev @neutrinojs/airbnb

Project Layout

@neutrinojs/airbnb follows the standard project layout specified by Neutrino. This means that by default all project source code should live in a directory named src in the root of the project.

Quickstart

After adding the Airbnb preset to your Neutrino-built project, edit your project's package.json to add the preset for linting before your build preset. For example, when building your project using @neutrinojs/react:

{
  "scripts": {
    "start": "neutrino start --use @neutrinojs/airbnb @neutrinojs/react",
    "build": "neutrino build --use @neutrinojs/airbnb @neutrinojs/react"
  }
}

Or if you are using a .neutrinorc.js, add this preset to your use array instead of --use flags:

module.exports = {
  use: [
    '@neutrinojs/airbnb',
    '@neutrinojs/react'
  ]
};

Start the app, then check your console for any linting errors. If everything is successful, you should see no errors in the console. ESLint errors visible during development are reported, but will still continue to build and serve your project. ESLint errors during build will not build the project, and will cause the command to fail.

Yarn

❯ yarn start

✔ Development server running on: http://localhost:5000
✔ Build completed

ERROR in ./src/index.js

/react/src/index.js
  7:1   warning  Unexpected console statement                no-console
  7:14  error    A space is required after '{'               babel/object-curly-spacing
  7:20  error    Missing space before value for key 'hello'  key-spacing
  7:27  error    A space is required before '}'              babel/object-curly-spacing

✖ 4 problems (3 errors, 1 warning)

npm

❯ npm start

✔ Development server running on: http://localhost:5000
✔ Build completed

ERROR in ./src/index.js

/react/src/index.js
  7:1   warning  Unexpected console statement                no-console
  7:14  error    A space is required after '{'               babel/object-curly-spacing
  7:20  error    Missing space before value for key 'hello'  key-spacing
  7:27  error    A space is required before '}'              babel/object-curly-spacing

✖ 4 problems (3 errors, 1 warning)

Building

@neutrinojs/airbnb will cause errors to fail your build when creating a bundle via neutrino build. If you want to ease introduction of this linting preset to your project, consider only adding it to your use list for neutrino start or development environment until all linting errors have been resolved.

❯ yarn build

/react/src/index.js
  6:1   warning  Unexpected console statement            no-console
  6:14  error    A space is required after '{'           babel/object-curly-spacing
  6:16  error    Missing space before value for key 'a'  key-spacing
  6:17  error    A space is required before '}'          babel/object-curly-spacing

✖ 4 problems (3 errors, 1 warning)

error Command failed with exit code 1.

Example: ease linting into project by only adding when NODE_ENV=development, e.g. neutrino start:

module.exports = {
  use: [
    '@neutrinojs/react'
  ],
  env: {
    NODE_ENV: {
      development: {
        use: ['@neutrinojs/airbnb']
      }
    }
  }
};

Middleware options

This preset uses the same middleware options as @neutrinojs/eslint. If you wish to customize what is included, excluded, or any ESLint options, you can provide an options object with the middleware and this will be merged with our internal defaults for this preset. Use an array pair instead of a string to supply these options.

Example: Turn off semicolons from being required as defined by the Airbnb rules.

module.exports = {
  use: [
    ['@neutrinojs/airbnb', {
      eslint: {
        rules: {
          semi: 'off'
        }
      }
    }]
  ]
};

Customizing

To override the build configuration, start with the documentation on customization. @neutrinojs/airbnb creates some conventions to make overriding the configuration easier once you are ready to make changes.

Rules

The following is a list of rules and their identifiers which can be overridden:

| Name | Description | Environments and Commands | | --- | --- | --- | | lint | Lints JS and JSX files from the src directory using ESLint. Contains a single loader named eslint. This is inherited from @neutrinojs/eslint. | all |

Information

If you want your preset or middleware to also extend from another ESLint configuration or preset that you have made a dependency, you must use baseConfig.extends rather than just extends. This is a limitation of ESLint, not this middleware.

Override configuration

By following the customization guide and knowing the rule and loader IDs above, you can also override or augment the build by providing a function to your .neutrinorc.js use array. You can also make this change from the Neutrino API when using the use method.

Example: Turn off semicolons from being required as defined by the Airbnb rules from .neutrinorc.js using a function and the API:

module.exports = {
  use: [
    '@neutrinojs/airbnb',
    (neutrino) => neutrino.config.module
      .rule('lint')
      .use('eslint')
      .tap(options => Object.assign({}, options, {
        rules: {
          semi: 'off'
        }
      }))
  ]
};

eslint CLI

This is the recommended way to perform a one-off lint in a Neutrino project, and is inherited from @neutrinojs/eslint.

You can also have Neutrino invoke ESLint for you if you wish to perform a one-time lint. This avoids needing to install ESLint manually, creating a .eslintrc.js file, or having to manage includes and ignores. As long as the ESLint middleware is loaded, you have access to a command to run ESLint from the command line.

This middleware registers a command named lint which programmatically calls ESLint and prints the results to the console.

❯ neutrino lint

❯ neutrino lint --fix

eslintrc Config

If you cannot or do not wish to use Neutrino to execute one-off linting, you can still use ESLint manually.

@neutrinojs/eslint, from which this preset inherits, also provides a method for getting the ESLint configuration suitable for use in an eslintrc file. Typically this is used for providing hints or fix solutions to the development environment, e.g. IDEs and text editors. Doing this requires creating an instance of the Neutrino API and providing the middleware it uses. If you keep all this information in a .neutrinorc.js, this should be relatively straightforward. By providing all the middleware used to Neutrino, you can ensure all the linting options used across all middleware will be merged together for your development environment, without the need for copying, duplication, or loss of organization and separation.

This middleware registers another command named eslintrc which returns an ESLint configuration object suitable for consumption by the ESLint CLI. Use the Neutrino API's call method to invoke this command:

Example: Create a .eslintrc.js file in the root of the project, using .neutrinorc.js middleware.

// .eslintrc.js
const { Neutrino } = require('neutrino');

// Specify middleware to Neutrino prior to calling eslintrc.
// Even if using .neutrinorc.js, you must specify it when using
// the API
module.exports = Neutrino()
  .use('.neutrinorc.js')
  .call('eslintrc');

Example: Create a .eslintrc.js file in the root of the project, using specified middleware.

// .eslintrc.js
const { Neutrino } = require('neutrino');

// Specify middleware to Neutrino prior to calling eslintrc.
// You can choose to not use .neutrinorc.js as the middleware to
// use if you prefer, specifying any middleware you wish.
module.exports = Neutrino()
  .use('@neutrinojs/airbnb', {
    eslint: {
      rules: { semi: 'off' }
    }
  })
  .use('@neutrinojs/react')
  .call('eslintrc');

If you are able, only use a .eslintrc.js file for editor hints, and use the Neutrino lint command for one-off linting or fixes.

Projects may face a problem when their editor or IDE lints all files and highlights errors that were normally excluded from source, i.e. Neutrino's include and exclude options. This is because the ESLint CLI does not have a way to specify included and excluded files from configuration. If you still wish to use ESLint's CLI for linting, consider setting CLI flags or using an eslintignore to choose which files to include or exclude from linting.

Unfortunately ESLint does not provide the possibility to configure ignored paths from Neutrino configuration and exclude them from linting. Projects authors should define this manually in their project root directory in a .eslintignore file. This is one of the main reasons to prefer using the lint CLI command with this middleware, as it avoids a lot of manual configuration and boilerplate.

.eslintignore file:

/build
/*.*

ESLint will exclude built files and any files in the root directory (e.g. custom Neutrino configuration) but src and test folders will be still checked. node_modules are ignored by default in ESLint. More information can be found in the ESLint user guide.

Contributing

This preset is part of the neutrino-dev repository, a monorepo containing all resources for developing Neutrino and its core presets and middleware. Follow the contributing guide for details.