eslint-stdout

A custom ESLint formatter that outputs fixed source code to stdout while displaying errors on stderr. This formatter is designed to work with tools like git-format-staged for pre-commit hooks.

How It Works

1. Fixed output to stdout: The formatter outputs the fixed source code (when available) to stdout
2. Errors to stderr: Any linting errors are formatted using eslint-friendly-formatter and sent to stderr
3. Multiple files: When processing multiple files, outputs are separated by null characters (\0)
4. Ignored files: No output is produced for files that ESLint is configured to ignore

This separation allows tools like git-format-staged to capture the fixed code while still displaying linting errors to the user.

Installation

npm install --save-dev eslint-stdout
# or
yarn add --dev eslint-stdout
# or
bun add -d eslint-stdout

Usage

Quick Start with git-format-staged

This package includes a convenient eslint-stdout command that can be used directly with git-format-staged:

#!/bin/sh
git-format-staged --verbose -f \
  "eslint-stdout '{}'" \
  '*.js' '*.ts' '*.jsx' '*.tsx'

The eslint-stdout command automatically:

• Changes to the file's directory for local config support
• Runs ESLint with --fix-dry-run to generate fixes
• Outputs the fixed code to stdout
• Displays any errors to stderr

Using as an ESLint Formatter

You can also use it directly as an ESLint formatter:

eslint --format eslint-stdout --fix-dry-run your-file.js

Example

# Run ESLint with fixes and capture both outputs
eslint --format eslint-stdout --fix-dry-run src/**/*.js > fixed-output.js 2> errors.log

License

MIT