CoffeeLint

2.1.0 verified Fri May 01 auth: no javascript

CoffeeLint is a style checker for CoffeeScript that helps keep code consistent and avoid common mistakes. Version 2.1.0 (stable, released 2019) targets Node.js >=6.9.1. It provides over 20 built-in rules covering spacing, naming, and syntax pitfalls. Alternatives like coffeelint-stylish offer custom reporters, but CoffeeLint remains the standard linter for the CoffeeScript ecosystem.

Common errors

error TypeError: config is not a function ↓

cause Calling lint(source, configFunction) instead of lint(source, config). require('coffeelint') is not the lint function.

fix

Use coffeelint.lint(source, config) – note, coffeelint is required, not coffeelint.lint.

error Error: Cannot find module 'coffee-script' ↓

cause coffee-script is a peer dependency not automatically installed.

fix

Run npm install coffee-script --save-dev

error Ignoring file because extension is not .coffee or .litcoffee ↓

cause CoffeeLint only scans .coffee and .litcoffee files by default.

fix

Pass a custom glob pattern or rename your file to have .coffee extension.

Warnings

breaking v2.0.0 dropped Node.js 4 support; requires Node >=6.9.1. ↓

fix Update Node.js to v6.9.1 or later.

deprecated Rule 'no_tabs' is deprecated in favor of 'indentation'. ↓

fix Use 'indentation' rule with 'tabs' option.

gotcha Config option 'level' for a rule is case-sensitive; only 'error', 'warn', or 'ignore' accepted. ↓

fix Ensure level strings are lowercase exactly.

gotcha CoffeeLint uses its own CoffeeScript parser (coffee-script) and may produce different results than the official compiler version. ↓

fix Pin coffee-script version to match your project's compiler version.

Install

npm install coffeelint

yarn add coffeelint

pnpm add coffeelint

Imports

coffeelint

wrong

import coffeelint from 'coffeelint';

correct

const coffeelint = require('coffeelint');

CoffeeLint does not ship ES modules; use CommonJS require.

coffeelint.lint
wrong
```
coffeelint.lint(source, options);
```
correct
```
coffeelint.lint(source, config, options);
```
Second argument must be a config object (may be empty). Only two positional args besides optional callback.
coffeelint.registerRule
wrong
```
coffeelint.registerRule(rule);
```
correct
```
coffeelint.registerRule(rule, ruleName);
```
registerRule requires ruleName as second argument.

Quickstart

Lints a CoffeeScript file using a custom config and prints errors to console.

const coffeelint = require('coffeelint');
const fs = require('fs');
const source = fs.readFileSync('./example.coffee', 'utf8');
const config = {
  max_line_length: {
    level: 'warn',
    value: 80
  },
  no_trailing_whitespace: {
    level: 'error'
  }
};
const errors = coffeelint.lint(source, config);
if (errors.length) {
  errors.forEach(err => console.log(`Line ${err.lineNumber}: ${err.message} (${err.rule})`));
} else {
  console.log('No lint errors!');
}