convertTimeFormat.ts

 /* Converts a time string between 12-hour and 24-hour formats.
 *  Made with ❤️ with TypeScript by Alvison Hunter - November 16th, 2024.
 * 
 * @param {string} hour - The time string to convert. 
 *                        For 12-hour format, use "hh:mm:ss AM/PM".
 *                        For 24-hour format, use "HH:mm:ss".
 * @param {boolean} isMilitaryFormat - If `true`, converts from 12-hour to 24-hour format.
 *                                     If `false`, converts from 24-hour to 12-hour format.
 * @returns {string} - The converted time string.
 *                     For 24-hour format, returns "HH:mm:ss".
 *                     For 12-hour format, returns "hh:mm:ss AM/PM".
 */
const convertTimeFormat = (hour: string, isMilitaryFormat: boolean): string => {
    if (isMilitaryFormat) {
        // Convert 12-hour format to 24-hour format
        const [time, meridian] = hour.split(/(AM|PM)/i);
        let [h, m, s] = time.trim().split(":").map(Number);
        if (meridian === "PM" && h !== 12) h += 12;
        if (meridian === "AM" && h === 12) h = 0;
        return `${String(h).padStart(2, "0")}:${String(m || 0).padStart(2, "0")}:${String(s || 0).padStart(2, "0")}`;
    } else {
        // Convert 24-hour format to 12-hour format
        let [h, m, s] = hour.split(":").map(Number);
        const meridian = h >= 12 ? "PM" : "AM";
        h = h % 12 || 12; // Convert 0 to 12 for 12-hour format
        return `${h}:${String(m || 0).padStart(2, "0")}:${String(s || 0).padStart(2, "0")} ${meridian}`;
    }
}

// Example usage:
console.log(convertTimeFormat("02:30:16 PM", true)); // "14:30:16" 
console.log(convertTimeFormat("14:30", false));   // "2:30:00 PM" 
console.log(convertTimeFormat("17:40", false));   // "5:40:00 PM" 
console.log(convertTimeFormat("03:16:22", true));   // "03:16:22"