code-quality

Domain 2: Code Quality & Standards

2.1 WordPress Coding Standards (WPCS)

• PHP code adheres to WordPress PHP Coding Standards
• JavaScript follows WordPress JS Coding Standards
• CSS follows WordPress CSS Coding Standards
• HTML follows WordPress HTML Coding Standards
• Yoda conditions used for comparisons (if ( true === $var ))
• Proper indentation (tabs, not spaces for PHP; as per standard for JS/CSS)
• PHPDoc blocks present for all functions, classes, methods, hooks
• Text domain consistency for internationalization

2.2 Static Analysis

• PHPCS with WordPress-Extra and WordPress-VIP-Go rulesets
• PHPStan at level 6+ (ideally max) with WordPress extensions
• Psalm analysis for type safety
• ESLint for JavaScript with WordPress preset
• Stylelint for CSS/SCSS

2.3 Architecture & Design Patterns

• Proper use of WordPress hooks system (actions and filters) — no function overriding via copy-paste
• Single Responsibility Principle in custom classes
• Proper namespacing to avoid function/class name collisions
• Autoloading via PSR-4 or WordPress-compatible patterns
• Data validation at boundaries (input validation, output escaping)
• Proper separation of concerns (business logic vs presentation)
• No business logic in template files
• Proper use of WordPress transients API for caching expensive operations
• Custom post types and taxonomies registered correctly with appropriate capabilities
• Options API used correctly (autoloaded only when necessary)

2.4 Error Handling

• Try/catch blocks around operations that can fail (API calls, file operations, database)
• WordPress error pattern: return WP_Error objects rather than false or exceptions for API boundaries
• Error conditions handled gracefully — no white screens
• Admin notices for recoverable errors
• Logging for non-recoverable errors without exposing details to users

2.5 Deprecated & Removed Functions

• No use of functions deprecated in current WordPress version
• No use of PHP functions deprecated in current PHP version
• No use of MySQL functions replaced by MySQLi/PDO
• mysql_* functions completely absent
• create_function() replaced with closures
• each() replaced with foreach

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Tool Usage: Code Quality Analysis Commands

WordPress Coding Standards

# Install WordPress Coding Standards
composer require --dev wp-coding-standards/wpcs

# Run PHPCS with WordPress standards
phpcs --standard=WordPress /path/to/plugin-or-theme

# Run with specific rulesets
phpcs --standard=WordPress-Extra /path/to/plugin
phpcs --standard=WordPress-VIP-Go /path/to/plugin

Static Analysis Tools

# PHPStan (static analysis)
composer require --dev phpstan/phpstan szepeviktor/phpstan-wordpress
phpstan analyse --level=max /path/to/src

# Psalm (type safety)
composer require --dev vimeo/psalm
psalm --init
psalm

# PHP Linting (syntax check)
find /path/to/plugin -name "*.php" -exec php -l {} \;

JavaScript and CSS

# ESLint with WordPress preset
npm install --save-dev eslint @wordpress/eslint-plugin
eslint /path/to/js-files

# Stylelint for CSS
npm install --save-dev stylelint stylelint-config-wordpress
stylelint "**/*.css"