# Silvermine ESLint Rules

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## What?

Shareable [ESLint](http://eslint.org/) configuration for all Silvermine projects.


## Why?

Because we need it. Whitespace errors are evil. As are the other hundreds of
types of errors this protects us from.

## Running ESLint

It is recommended to run ESLint via a NPM script in `package.json` with the command
`eslint .` for  projects that use this configuration.

Example:

```json
{
   "scripts": {
      "eslint": "eslint ."
   }
}
```

## Other Configuration Files Available

In addition to the ESLint rules, this package provides configuration for the following:

   * [EditorConfig](https://editorconfig.org/)
      * Provides a default set of editor configuration values to use in Silvermine projects
      * Usage: Symlink the .editorconfig file to the root of your project and use the
        appropriate extension for your editor.
      * `ln -s ./node_modules/@silvermine/eslint-config/.editorconfig`
   * [commitlint](https://conventional-changelog.github.io/commitlint/)
      * Provides linting for commit messages of Silvermine projects
      * Usage: Add a `commitlint.config.js` file to the root of the project with the
        following and then set up commitlint in the project:

        ```javascript
        'use strict';

        module.exports = {
           extends: [ '@silvermine/eslint-config/commitlint' ],
        };
        ```


## Notes on Semantic Versioning

See the [notes we made in eslint-plugin-silvermine][semver-notes] regarding our use of
version numbers here. The same decisions made for that repo also apply to this repo,
basically for the same reasons.

[semver-notes]: https://github.com/silvermine/eslint-plugin-silvermine/#note-on-semantic-versioning


## What version should I use?

When choosing which version of this config to use, consider the following:

   * v2.x.x is the newest branch of our config, which allows for ES2015+ features, as well
     as TypeScript linting. On new projects, we recommend using this branch of the config.
   * v1.x.x is the legacy version of our eslint config. This should primarily be used in
     legacy es5 projects and with node version < 8.10.0. It does not allow for many
     es2015+ features, such as spread/rest operators and arrow functions.
      * The v1.x.x branch is not recommended for use in new projects and will only be
        minimally updated with bug fixes to support legacy code.

## Updating ESLint

Updating ESLint in this project requires multiple steps across both this project and
[@silvermine/eslint-plugin](https://github.com/silvermine/eslint-plugin-silvermine):

1. Open a PR to update ESLint in @silvermine/eslint-plugin
   * Note: Linting in the @silvermine/eslint-plugin PR will likely fail because
    @silvermine/eslint-plugin's version of @silvermine/eslint-config is incompatible with
    the new version of ESLint. That's ok. We will fix it soon in a subsequent step.
2. After the PR from step 1 is merged, update @silvermine/eslint-plugin in
   @silvermine/eslint-config using a `git+https` + git hash URL. The git hash should point
   to the commit in @silvermine/eslint-plugin where you updated ESLint.
3. Update ESLint in @silvermine/eslint-config. Open a PR that contains this update and
   the @silvermine/eslint-plugin update from step 2.
      * Note: All of the linting and tests in this build should pass.
4. Publish a new version of @silvermine/eslint-config to the NPM registry
5. Update @silvermine/eslint-config in @silvermine/eslint-plugin to the version that was
   just published
      * Note: All of the linting and tests in this build should now pass.
6. Publish a new version of @silvermine/eslint-plugin to the NPM registry
7. Update @silvermine/eslint-plugin in @silvermine/eslint-config using the version that was
   just published

## License

This software is released under the MIT license. See [the license
file](LICENSE) for more details.