W2Moment: A Custom Date and Time Management Library

Overview

The W2Moment library is a lightweight, custom-built utility for managing dates and times with features inspired by Moment.js.. It provides a wide range of functionality for formatting, parsing, manipulating, and displaying dates and times.

Features

Format dates and times using custom patterns (e.g., YYYY-MM-DD, MMMM Do YYYY).

Parse dates from strings with specific formats (e.g., YYYYMMDD).

Manipulate dates by adding or subtracting units of time (days, hours, minutes, seconds).

Display relative time (e.g., 13 years ago, 5 hours ago).

Implement calendar-based display (e.g., Today at 11:22 PM, Last Saturday at 11:22 PM).

Locale support for customizing months and weekdays.

Installation

Simply include the W2Moment class in your JavaScript project as follows: npm i w2moment

import W2Moment from "./src/w2moment.js";
Usage Examples
Formatting Dates

const moment = new W2Moment("20250325", "YYYYMMDD");
console.log(moment.format("YYYY")); // Output: 2025
console.log(moment.format("MMMM")); // Output: March
console.log(moment.format("L"));    // Output: 03/25/2025
console.log(moment.format("LL"));   // Output: March 25, 2025
Relative Time (fromNow)

const pastMoment = new W2Moment("20111031", "YYYYMMDD");
console.log(pastMoment.fromNow(new Date("2025-03-25"))); // Output: 13 years ago

const futureMoment = new W2Moment("20301031", "YYYYMMDD");
console.log(futureMoment.fromNow(new Date("2025-03-25"))); // Output: 5 years ago

Adding and Subtracting Time

const moment2 = new W2Moment(new Date("2025-03-25"));
console.log(moment2.add(1, "days").format("YYYY-MM-DD")); // Output: 2025-03-26
console.log(moment2.subtract(2, "days").format("YYYY-MM-DD")); // Output: 2025-03-24

Calendar Display

const testMoment = new W2Moment();

console.log(testMoment.subtract(10, "days").calendar()); // Output: 03/16/2025
console.log(testMoment.subtract(6, "days").calendar());  // Output: Last Wednesday at 11:22 PM
console.log(testMoment.subtract(3, "days").calendar());  // Output: Last Saturday at 11:22 PM
console.log(testMoment.subtract(1, "days").calendar());  // Output: Yesterday at 11:22 PM
console.log(testMoment.calendar());                     // Output: Today at 11:22 PM
console.log(testMoment.add(1, "days").calendar());       // Output: Tomorrow at 11:22 PM
console.log(testMoment.add(3, "days").calendar());       // Output: Friday at 11:22 PM
console.log(testMoment.add(10, "days").calendar());      // Output: 04/04/2025

Locale Support

const todayMoment = new W2Moment(new Date("2025-03-25"));
console.log(todayMoment.locale()); // Output: en

Test Cases To validate the functionality of W2Moment, you can use the provided custom test framework:

const expect = (actual) => {
  return {
    toBe(expected) {
      if (actual === expected) {
        console.log("Test Passed");
      } else {
        console.error(`Test Failed: Expected ${expected}, but got ${actual}`);
      }
    },
    toEqual(expected) {
      if (JSON.stringify(actual) === JSON.stringify(expected)) {
        console.log("Test Passed");
      } else {
        console.error(
          `Test Failed: Expected ${JSON.stringify(expected)}, but got ${JSON.stringify(actual)}`
        );
      }
    },
  };
};

Sample Tests

const moment1 = new W2Moment(new Date("2025-03-25 21:55:35"));
expect(moment1.format("LT")).toBe("09:55 PM");
expect(moment1.format("LTS")).toBe("09:55:35 PM");
expect(moment1.format("LLLL")).toBe("Tuesday, March 25, 2025 09:55 PM");

API Reference Constructor

new W2Moment(date = new Date(), format = null)

date: A JavaScript Date object or a date string.

format: Optional format string for parsing (e.g., YYYYMMDD).

Methods format(formatStr): Formats the date using the specified pattern.

fromNow(referenceDate): Displays relative time between the current date and the referenceDate.

add(amount, unit): Adds a specified amount of time (in days, hours, etc.).

subtract(amount, unit): Subtracts a specified amount of time (in days, hours, etc.).

startOf(unit): Sets the time to the beginning of the specified unit (day, hour).

endOf(unit): Sets the time to the end of the specified unit (day, hour).

calendar(referenceDate): Returns a calendar-style string representation of the date.

locale(locale): Sets the locale for month and weekday formatting.

License Feel free to use, modify, and distribute W2Moment as needed for your projects. Contributions are welcome!