datetime-fcs/src/index.js

A library to format dates, track countdowns, and calculate durations.

// src/index.js
import { format, differenceInSeconds, parseISO } from "date-fns";

/**
 * Countdown function: Returns remaining time until a target date.
 * @param {string} endTime - Target end time in ISO format.
 * @returns {string} Countdown in the format 'X hours, Y minutes, Z seconds'.
 */
export const countdown = (endTime) => {
  const now = new Date();
  const target = parseISO(endTime);
  const secondsRemaining = differenceInSeconds(target, now);

  if (secondsRemaining <= 0) {
    return "The countdown has ended!";
  }

  const hours = Math.floor(secondsRemaining / 3600);
  const minutes = Math.floor((secondsRemaining % 3600) / 60);
  const seconds = secondsRemaining % 60;

  return `${hours} hours, ${minutes} minutes, ${seconds} seconds remaining`;
};

/**
 * Format a given date to a specific format.
 * @param {string} date - The date string to format.
 * @param {string} formatString - The desired format (e.g., "yyyy-MM-dd HH:mm:ss").
 * @returns {string} Formatted date.
 */
export const formatDate = (date, formatString) => {
  return format(new Date(date), formatString);
};

/**
 * Calculate duration between two dates.
 * @param {string} startDate - The start date (ISO format).
 * @param {string} endDate - The end date (ISO format).
 * @returns {string} Duration in the format 'X hours, Y minutes, Z seconds'.
 */
export const durationBetweenDates = (startDate, endDate) => {
  const start = parseISO(startDate);
  const end = parseISO(endDate);
  const durationInSeconds = differenceInSeconds(end, start);

  const hours = Math.floor(durationInSeconds / 3600);
  const minutes = Math.floor((durationInSeconds % 3600) / 60);
  const seconds = durationInSeconds % 60;

  return `${hours} hours, ${minutes} minutes, ${seconds} seconds`;
};