husky eslint does not exit with 1

3 min read 26-02-2025

Husky is a popular Git hook manager that helps enforce pre-commit checks, ensuring code quality before commits are made. Often paired with ESLint for JavaScript linting, Husky ensures that code adheres to style guides and best practices. However, sometimes you might encounter an issue where Husky's ESLint hook doesn't exit with a non-zero exit code (specifically, 1), even when linting errors exist. This article explores the common causes and provides solutions to this problem.

Understanding the Problem: Why Exit Code 1 Matters

When ESLint detects errors, it's expected to return an exit code of 1, signaling to Husky that the commit should be aborted. If ESLint exits with code 0 (success), the commit proceeds regardless of any linting issues. An exit code of 1 correctly halts the commit process, enforcing your code quality rules. If ESLint doesn't exit with 1 when errors are present, your Husky pre-commit hook becomes ineffective.

Common Causes and Troubleshooting Steps

Let's investigate the typical reasons why your Husky ESLint setup might not be returning the expected exit code.

1. Incorrect Husky Configuration

Problem: The most frequent cause is an incorrectly configured husky section in your package.json. Ensure you're using the correct command and that it's properly linked to your ESLint configuration.
Solution: Verify your package.json file. It should look something like this (adjust paths as necessary):

{
  "husky": {
    "hooks": {
      "pre-commit": "npm run lint"
    }
  },
  "scripts": {
    "lint": "eslint ."
  }
}

Important: Ensure the lint script accurately runs ESLint. You may need to adjust the path to your project's source code (eslint . or eslint src/ etc). If you're using a different package manager (Yarn, pnpm), adapt the scripts accordingly.
Reinstall Husky: Try reinstalling Husky: npm install husky --save-dev

2. ESLint Configuration Issues

Problem: Problems with your ESLint configuration (.eslintrc.js or .eslintrc.json) can prevent it from reporting errors correctly. Incorrect rules, missing plugins, or configuration errors can all lead to this problem.
Solution:
- Check for Errors: Carefully review your ESLint configuration file for any syntax errors or misconfigurations. A simple typo can prevent it from working correctly.
- Rule Severity: Make sure your ESLint rules are set to error and not warn. Warnings (severity 1) won't cause ESLint to exit with code 1. Only error (severity 2) level rules will. Example:

module.exports = {
  rules: {
    "no-unused-vars": "error", // This will cause a failure
    "semi": "warn"             // This will be ignored by the pre-commit hook
  }
};

* **Run ESLint Manually:** Try running ESLint directly from your terminal (`npm run lint` or `yarn lint`). Observe the output – any errors displayed there should also trigger the exit code. If errors don't show up here, there's a problem with ESLint itself.

3. Conflicting Dependencies or Plugins

Problem: Conflicts between different packages or plugins can interfere with ESLint's functionality.
Solution:
- Check package.json: Look for any conflicting or outdated packages. Try updating dependencies: npm update or yarn upgrade.
- Temporarily Disable Plugins: If you have many ESLint plugins, try temporarily disabling some to see if one of them is the cause.

4. Incorrect Shell Configuration

Problem: Sometimes the shell used by Husky might not be compatible with the way ESLint is executed, which can lead to an incorrect exit code.
Solution: Try specifying the shell explicitly within your husky config, for example in your package.json:

{
  "husky": {
    "hooks": {
      "pre-commit": "npx --no-install --yes npm run lint" // This uses npm directly within the npx environment
    }
  },
  "scripts": {
    "lint": "eslint ."
  }
}

5. Husky Installation Issues

Problem: If Husky is not installed correctly, or an outdated version, it might not execute scripts appropriately.
Solution: Remove Husky and reinstall:
```
npm uninstall husky
npm install husky --save-dev
```
After reinstalling, make sure to add the pre-commit hook again (if it's not present after reinstall). You might need to run npx husky install

Prevention and Best Practices

Regular Updates: Keep your ESLint, Husky, and Node.js versions updated.
Clear Logging: Add logging to your scripts to better debug problems. For example, you could print the ESLint exit code within your lint script.
Version Control: Use version control (Git) diligently to manage changes and roll back if necessary.

By systematically addressing these points, you should be able to identify and resolve the issue of Husky ESLint not exiting with 1, ensuring your pre-commit linting effectively maintains code quality. Remember to test frequently after making changes to your configuration.