Integrating working dates into web applications can be complex due to JavaScript's limited native support for advanced date operations, prompting developers to rely on third-party libraries for enhanced functionality. Moment.js, one of the earliest and most well-known libraries, offers a robust API and a variety of plugins for internationalization and formatting, although its mutable objects and larger file size have led to the development of alternatives like DayJS and Luxon. DayJS provides a similar API with a substantially smaller file size, while Luxon builds on modern browser APIs for internationalization, offering immutable objects. Date-fns emphasizes modular imports and immutability, supporting over 140 functions grouped by file. Meanwhile, libraries like ms focus on converting date formats to milliseconds, and js-joda offers an extensible framework for cleaner OOP code. Spacetime targets timezone management with a Moment.js-like API, highlighting the diverse approaches available for handling date and time complexities in JavaScript.