Intl DateTime Calendar

A WordPress plugin that displays dates and times in various calendar systems using the ECMAScript Internationalization API (Intl) while maintaining SEO friendliness.

Features

• Support for multiple calendar systems (Gregorian, Buddhist, Chinese, Hebrew, Islamic, etc.)
• Configurable date and time formatting styles
• Automatic localization based on language settings
• Full support for WordPress block editor (Gutenberg)
• SEO-friendly implementation (original datetime values are preserved in the HTML)
• Lightweight with no jQuery dependency
• Optimized with minified JavaScript for production

Usage

Once activated, the plugin will automatically format all dates and times on your site according to your selected calendar system and locale.

Configuration

1. Go to 'Settings' > 'Intl DateTime Calendar' in the WordPress admin
2. Select your preferred calendar system (Gregorian, Buddhist, Chinese, etc.)
3. Choose your locale (e.g., 'en', 'th-TH', 'ja-JP')
4. Set date and time style preferences (Full, Long, Medium, Short)
5. Save changes

Calendar Systems

The plugin supports the following calendar systems:

• buddhist: Buddhist Calendar
• chinese: Chinese Calendar
• coptic: Coptic Calendar
• dangi: Dangi (Korean) Calendar
• ethioaa: Ethiopic (Amete Alem) Calendar
• ethiopic: Ethiopic Calendar
• gregory: Gregorian (Western) Calendar
• hebrew: Hebrew Calendar
• indian: Indian Calendar
• islamic: Islamic Calendar
• islamic-civil: Islamic (Civil) Calendar
• islamic-rgsa: Islamic (Saudi Arabia) Calendar
• islamic-tbla: Islamic (Tabular) Calendar
• islamic-umalqura: Islamic (Umm al-Qura) Calendar
• iso8601: ISO 8601 Calendar
• japanese: Japanese Calendar
• persian: Persian Calendar
• roc: Republic of China Calendar

Date and Time Styles

Each style provides a different level of formatting detail:

• full: e.g., "Wednesday, December 31, 2023"
• long: e.g., "December 31, 2023"
• medium: e.g., "Dec 31, 2023"
• short: e.g., "12/31/23"

Advanced Usage

Manual Integration

If you need to format a specific date manually in your theme or plugin, you can use this format:

<?php
$timestamp = strtotime('2023-12-31 23:59:59') * 1000; // Convert to milliseconds for JS
?>

<span class="intl-datetime intl-datetime-auto" 
      data-intl-datetime="<?php echo esc_attr($timestamp); ?>" 
      data-calendar="buddhist" 
      data-locale="th-TH" 
      data-date-style="full" 
      data-time-style="long">
    December 31, 2023
</span>

JavaScript API

You can also format dates programmatically using the provided JavaScript API:

// Example: Format the current date
const timestamp = Date.now();
const options = {
    calendar: 'buddhist',
    locale: 'th-TH',
    dateStyle: 'full',
    timeStyle: 'long'
};

const formatter = new Intl.DateTimeFormat(options.locale, {
    calendar: options.calendar,
    dateStyle: options.dateStyle,
    timeStyle: options.timeStyle
});

const formattedDate = formatter.format(new Date(timestamp));
console.log(formattedDate);

Browser Compatibility

This plugin utilizes the Intl API, which is supported in all modern browsers:

• Chrome 76+
• Firefox 72+
• Safari 14+
• Edge 79+

For older browsers, the plugin will fall back to the browser's default date formatting.

Updates

The plugin automatically checks for updates from the GitHub repository. When a new version is released, you'll receive an update notification in your WordPress admin dashboard.

Contributing

Contributions are welcome! Please feel free to submit a Pull Request.

License

This plugin is licensed under the GPL v2 or later.