Fixing the prettier eslint line endings CRLF LF warnings

It's common to get the line endings errors or warnings when you setup working on a fresh codebase. Let's see what it is and how to resolve it.

Introduction

When setting up a new codebase, especially in a collaborative environment where different operating systems are involved, you might encounter line ending errors or warnings. These issues are common but can be resolved with a few straightforward steps. This blog will explore what line ending errors are and how to resolve them effectively.

What are Line Endings?

Line endings are special characters that signify the end of a line in a text file. Different operating systems use different characters for line endings:

• LF (Line Feed, \n): Used by Unix-based systems like Linux and macOS.
• CRLF (Carriage Return + Line Feed, \r\n): Used by Windows.
• CR (Carriage Return, \r): Historically used by older Mac systems (pre-OS X).

Common Line Ending Errors

When you work on a codebase across different operating systems, line ending inconsistencies can arise. These inconsistencies can lead to errors or warnings in your code editor or version control system. Common issues include:

• Merge Conflicts: Different line endings can cause unnecessary merge conflicts in version control.
• Build Failures: Some build systems or scripts might fail if they encounter unexpected line endings.
• Linter/Formatter Warnings: Tools like ESLint or Prettier can generate warnings or errors due to inconsistent line endings.

Resolving Line Ending Issues

1. Configuring Your Editor

Most modern editors allow you to configure the line endings. Here’s how you can set it up in Visual Studio Code (VSCode):

1. Open Settings: Go to File > Preferences > Settings (or use Ctrl + ,).
2. Search for end of line: Set it to your preferred line ending (LF for macOS/Linux, CRLF for Windows).

// settings.json
{
  "files.eol": "\n" // Use LF for macOS/Linux
  // "files.eol": "\r\n"  // Use CRLF for Windows
}

2. Configuring Git

Git can automatically handle line ending normalization, ensuring consistent line endings across different platforms.

• For LF in the repository:

  git config --global core.autocrlf input
  

• For CRLF in the repository:

  git config --global core.autocrlf true
  

• To disable automatic conversion:

  git config --global core.autocrlf false
  

Additionally, you can create a .gitattributes file in your repository to enforce consistent line endings:

# .gitattributes
* text=auto

3. Configuring ESLint and Prettier

If you're using ESLint and Prettier, you can configure them to enforce consistent line endings and avoid related warnings or errors.

ESLint Configuration:

// .eslintrc.js
module.exports = {
  rules: {
    'linebreak-style': ['error', 'unix'], // For LF
    // 'linebreak-style': ['error', 'windows']  // For CRLF
  },
}

Prettier Configuration:

// .prettierrc
{
  "endOfLine": "lf" // Use "lf" for macOS/Linux
  // "endOfLine": "crlf"  // Use "crlf" for Windows
}

Disabling the Prettier endOfLine Rule: If you want to disable only the endOfLine rule in Prettier but keep other rules active, you can set it to auto:

// .eslintrc.js
module.exports = {
  extends: ['plugin:prettier/recommended'],
  rules: {
    'prettier/prettier': ['warn', { endOfLine: 'auto' }],
  },
}

Conclusion

Line ending errors and warnings are common when setting up a new codebase, but they can be managed effectively with proper configuration. By setting up your editor, Git, and tools like ESLint and Prettier correctly, you can ensure consistent line endings and avoid related issues. This will help maintain a clean and collaborative development environment, regardless of the operating systems in use.

I hope that was useful. Feel free to drop your comments below.

- Ayush 🙂