The provided benchmark tests the performance of two popular JavaScript libraries for date manipulation and formatting: Day.js and date-fns. The benchmark aims to compare how fast each library can perform certain operations on date objects, specifically parsing, formatting, and adding days to dates.
Libraries Being Compared
Day.js:
- Purpose: Day.js is a minimalist JavaScript library for manipulating dates. It provides a simple API that is similar to Moment.js but with a much smaller footprint. It emphasizes compatibility and efficiency, focusing on providing just the essentials for date handling.
- Key Features: Day.js allows users to parse, manipulate, and display dates easily. It is immutable (i.e., it does not change existing date objects), promoting a functional programming style.
date-fns:
- Purpose: date-fns is a library that provides a set of functions for manipulating dates in JavaScript. It is modular, meaning you can import only the functions you need, helping to keep bundle sizes small.
- Key Features: With date-fns, you can perform a wide range of date operations—parsing, formatting, and arithmetic—while maintaining a functional programming style.
Benchmark Tests
Each test case in the benchmark comprises three operations:
Parsing a Date:
- date-fns:
datefns.parseISO(window.ds)
- Day.js:
dayjs(ds)
- This operation converts a date string into a date object. Both libraries are evaluated on how efficiently they parse the input string.
Formatting the Current Date:
- date-fns:
datefns.format(new Date(), "mm-dd-yyyy")
- Day.js:
dayjs().format("MM-DD-YYYY")
- Here, both libraries format the current date into a specified string format. Differences in performance here reflect the efficiency of their internal formatting algorithms.
Adding Days to a Date:
- date-fns:
datefns.add(new Date(), { weeks: 1 })
- Day.js:
dayjs().add(1, 'days')
- This operation modifies a date object by advancing it by one week. The performance comparison highlights how each library handles date arithmetic.
Results
From the latest benchmark results:
- Day.js executed at approximately 216,675 operations per second.
- date-fns executed at approximately 203,851 operations per second.
The results indicate that Day.js is slightly faster in this benchmark scenario. However, the performance difference may vary based on the operations used and the environment in which the tests are run.
Pros and Cons
Day.js Pros:
- Compact size and simple API, making it easy to learn and integrate.
- Immutable data structures promote safer code.
- Fast performance across common tasks.
Day.js Cons:
- Fewer features than some larger libraries like Moment.js or even date-fns.
- Limited customization options compared to some other libraries.
date-fns Pros:
- Modular design allows importing only necessary functions, keeping project sizes minimal.
- Rich feature set; covers a wide range of date functionalities.
- Good performance, with support for tree-shaking and bundling optimizations.
date-fns Cons:
- Slightly larger bundle size if multiple functions are imported.
- More boilerplate may be required for certain operations compared to Day.js.
Other Considerations and Alternatives
- Moment.js: Once the dominant library for date manipulation in JavaScript, it has been deemed outdated for new projects due to its larger size and mutable API. It’s still widely used and offers extensive functionalities but is not recommended for new applications.
- Luxon: A modern library built by one of the Moment.js authors, it provides a rich API and includes features like timezone handling but is larger than Day.js and date-fns.
- Native Date API: JavaScript’s built-in
Date object can handle basic date operations without any library but lacks functionality for complex date manipulations and formatting.
In summary, this benchmark serves as a comparison of Day.js and date-fns regarding their performance in common date operations, guiding developers in choosing the right library for their date manipulation needs.
