I18N Standards

Internationalization (i18n) Standards

Apply these standards when working with user-facing strings in this project.

Background

Projects often accumulate a mix of hardcoded and translatable strings over time. This is a low-priority cleanup task — apply these standards gradually when you touch files that contain user-facing strings.

Quick Reference

PHP: User-Facing Strings (WordPress)

All user-facing strings should use WordPress translation functions with the project's text domain constant:

// Simple string
echo __('Save Changes', TEXT_DOMAIN);

// Echoing directly
_e('Submit Form', TEXT_DOMAIN);

// With placeholders
printf(
    __('Showing %d of %d results', TEXT_DOMAIN),
    $current,
    $total
);

// Pluralization
printf(
    _n('%d item', '%d items', $count, TEXT_DOMAIN),
    $count
);

Language Conventions

JavaScript Strings (WordPress)

Use @wordpress/i18n for Gutenberg/block editor strings:

import { __, _n, sprintf } from '@wordpress/i18n';

// Simple string — use the text domain string (not the PHP constant)
const label = __('Edit', 'my-theme');

// With placeholders
const message = sprintf(
    __('Showing %d results', 'my-theme'),
    count
);

When Refactoring

When you encounter hardcoded or mixed-language strings in a file you're editing:

1. Identify user-facing strings (displayed to users in browser)
2. Wrap them with __() or _e()
3. Keep code comments and internal messages in English
4. Don't translate:
   • Log messages
   • Debug output
   • Internal error messages not shown to users
   • API responses (unless they're user-facing error messages)

Text Domain

The text domain should be defined as a constant in the project's configuration:

define('TEXT_DOMAIN', 'my-theme');

Always use the text domain constant in PHP. In JavaScript, use the text domain string directly (JS doesn't have access to PHP constants).

Generating POT Files

After making i18n changes, regenerate the POT file:

# Using WP-CLI (if available)
wp i18n make-pot . languages/<text-domain>.pot --domain=<text-domain>

# Or using @wordpress/i18n npm package
npx @wordpress/i18n make-pot . languages/<text-domain>.pot

Checklist

When touching files with strings:

• User-facing PHP strings wrapped with __() or _e()
• User-facing JS strings use @wordpress/i18n
• Text domain constant used in PHP, text domain string in JS
• Code comments remain in English
• No hardcoded user-facing strings without translation wrapper
• Placeholders use printf()/sprintf() not concatenation

Priority

This is a low-priority gradual cleanup task. Don't create separate commits just for i18n changes — include them when you're already modifying a file for other reasons.