Custom ESLint rules

ESLint rules with modified behavior or additional options that won't be merged into upstream for "as designed" or "stylistic features frozen" etc. reasons.

• Installation
• Usage
• Rules
  • no-invalid-this
  • no-magic-numbers
  • no-underscore-dangle

Installation

Just clone the repo or download it as tarball and unpack

Usage

Improved rules could be used as replacements to stock ones (just move them to %{eslint}/lib/rules folder) but it's easier and more correct to add them as custom rule set.

• Via command line: run ESLint with parameter

  --rulesdir <path to ESLint-custom-rules>
  

• With VSCode and ESLint plugin by Dirk Baeumer - add following lines to settings.json (note rulePaths property not rulesdir!)

  "eslint.options": {
    "rulePaths": ["<path to ESLint-custom-rules>"]
  },

Rules

no-invalid-this

Modification: detects Node-specific event listener assignments and doesn't alert in these cases.

Issues: eslint/eslint#11349 ("Node-specific"), mysticatea/eslint-plugin-node#4 (no reaction)

Before:

process.on('exit', function() { console.log(this.argv); });
// Message "Unexpected 'this'"

After:

process.on('exit', function() { console.log(this.argv); });
// OK

no-magic-numbers

Modification: add ignoreConstDeclaration: boolean option which, if enabled, allows numbers in declaration of constants.

Issue: eslint/eslint#13239 ("As intended" + "freeze stylistic rules")

// no-magic-numbers: "error"
const MSEC_PER_MIN = 60 * 1000;
const DEF_OPTS = { timeout: 10 * MSEC_PER_MIN };
// Messages "No magic number: " for 60, 1000 and 10

// no-magic-numbers: ["error", { "ignoreConstDeclaration": true }]
const MSEC_PER_MIN = 60 * 1000;
const DEF_OPTS = { timeout: 10 * MSEC_PER_MIN };
// OK
let interv = 20 * MSEC_PER_MIN;
console.log( 1 * 2 * 3);
// Will still produce messages

no-underscore-dangle

Modification: add allowAfter: string[] option which defines list of identifiers after which dangling underscores are allowed.

PR: eslint/eslint#13590 ("Freeze stylistic rules")

// no-underscore-dangle: "error"
const self = this;
some.on('event', function() {
  self._private();
});
// Message "Unexpected dangling '_' in '_private'"

// no-underscore-dangle: ["error", { "allowAfter": [ "self" ] }]
const self = this;
some.on('event', function() {
  self._private();
});
// OK