JavaScript and PHP Date Formatting Functions with Validation

/**
 * Formats a date string and returns detailed information about it.
 * @param {string} dateString - The date in 'YYYY-MM-DD' format.
 * @param {Object} [config={}] - Configuration options.
 * @param {string} [config.locale='en-US'] - Locale for formatting.
 * @param {string} [config.format='full'] - Format style ('full', 'long', 'medium', 'short').
 * @returns {Object} An object containing the formatted date and date parts.
 * @throws {Error} If the input date or config is invalid.
 */
function formatDate(dateString, config = {}) {
    // Helper function to validate date components
    const isValidDate = (year, month, day) => {
        const date = new Date(year, month - 1, day);
        return date.getFullYear() === year &&
            date.getMonth() === month - 1 &&
            date.getDate() === day;
    };

    // Validate input format
    const dateRegex = /^(\d{4})-(0[1-9]|1[0-2])-(0[1-9]|[12]\d|3[01])$/;
    const match = dateString.match(dateRegex);

    if (!match) {
        throw new Error(`Invalid date format: "${dateString}". Expected 'YYYY-MM-DD'.`);
    }

    // Extract components from the matched regex
    const [, yearStr, monthStr, dayStr] = match;
    const year = parseInt(yearStr, 10);
    const month = parseInt(monthStr, 10);
    const day = parseInt(dayStr, 10);

    if (!isValidDate(year, month, day)) {
        throw new Error(`Invalid date: "${dateString}".`);
    }

    // Default and merged configuration
    const defaultConfig = { locale: 'en-US', format: 'full' };
    const mergedConfig = { ...defaultConfig, ...config };

    const supportedFormats = ['full', 'long', 'medium', 'short'];
    if (!supportedFormats.includes(mergedConfig.format)) {
        throw new Error(`Invalid format: "${mergedConfig.format}". Supported: ${supportedFormats.join(', ')}.`);
    }

    // Create Intl.DateTimeFormat instances
    const dateFormatter = new Intl.DateTimeFormat(mergedConfig.locale, {
        dateStyle: mergedConfig.format,
        timeZone: 'UTC'
    });

    const fullFormatter = new Intl.DateTimeFormat(mergedConfig.locale, {
        dateStyle: 'full',
        timeZone: 'UTC'
    });

    // Create date object
    const date = new Date(dateString);

    // Format the date and extract parts
    const formattedDate = dateFormatter.format(date);
    const parts = fullFormatter.formatToParts(date);

    // Safely extract parts
    const findPart = (type) => parts.find(part => part.type === type)?.value || '';
    const dayName = findPart('day');
    const weekdayName = findPart('weekday');
    const monthName = findPart('month');

    // Return the result object
    return {
        formatted: formattedDate,
        day: dayName,
        weekday: weekdayName,
        monthName,
        year,
        month,
        timestamp: date.getTime(),
        iso8601: date.toISOString(),
    };
}

// Example usages
try {
    // Example 1: Default configuration
    const result = formatDate('2024-12-10');
    console.log(result.formatted); // Tuesday, December 10, 2024
    // console.log(result.day); // 10
    // console.log(result.month); // 12
    // console.log(result.year); // 2024
    // console.log(result.weekday); // Tuesday
    // console.log(result.monthName); // December
    // console.log(result.timestamp); // 1733788800000
    // console.log(result.iso8601); // 2024-12-10T00:00:00.000Z

    // Example 2: Custom locale
    const example_2 = formatDate('2024-12-31', {
        locale: 'fr-FR',
    });
    console.log(example_2.formatted); // mardi 31 décembre 2024

    // Example 3: Medium format
    const example_3 = formatDate('2024-12-31', {
        locale: 'en-US',
        format: 'medium'
    });
    console.log(example_3.formatted); // Dec 31, 2024

    // Example 4: Short format
    const example_4 = formatDate('2024-12-31', {
        format: 'short'
    });
    console.log(example_4.formatted); // 12/31/24

    // Example 5: Invalid date format
    const example_5 = formatDate('2023-02-29', {
        format: 'full'
    });
    console.log(example_5.formatted); // Error: Invalid date: "2023-02-29".

} catch (error) {
    console.error("Example 5 Error:", error.message);
}

function extractDateParts(date) {
    // If no date is provided, use current date
    const targetDate = date ? new Date(date) : new Date();

    return {
        day: targetDate.getDate(),
        month: targetDate.getMonth() + 1, // Note: Months are 0-indexed
        year: targetDate.getFullYear()
    };
}

// Example usages
console.log(extractDateParts()); // Current date

console.log(extractDateParts('2024-05-15')); // {day: 15, month: 5, year: 2024}