The benchmark named "Date constructor performance" aims to compare the performance of different types of inputs to the JavaScript Date constructor. The benchmark is structured to measure how efficiently the JavaScript engine can parse various date formats and scenarios.

Test Cases Overview

1. new Date(full string):

   • Benchmark Definition: date = new Date('2023-09-18T16:29:10.093Z');
   • Description: This test uses a complete ISO 8601 string with time and timezone information.
   • Pros: The full string provides a precise representation of a specific moment in time.
   • Cons: Parsing such detailed strings may require more processing power than simpler formats.

2. new Date(short string):

   • Benchmark Definition: date = new Date('2023-09-18');
   • Description: This test uses a shorter date string that omits time and timezone.
   • Pros: Shorter strings are easier and faster to parse, as they provide less information to interpret.
   • Cons: Lacks detail like time and timezone, which may be necessary for applications requiring exact timestamps.

3. new Date(number):

   • Benchmark Definition: date = new Date(1695054550093);
   • Description: This test uses a timestamp in milliseconds since the Unix Epoch, which corresponds to 2023-09-18T16:29:10.093Z.
   • Pros: Numeric input is typically the fastest to process since it bypasses string parsing.
   • Cons: Less human-readable and requires conversion for clarity in applications.

4. new Date():

   • Benchmark Definition: date = new Date();
   • Description: Tests the performance of creating a Date object for the current date and time.
   • Pros: Directly captures the current moment without any parsing.
   • Cons: Performance may vary depending on how the JavaScript engine is optimized for real-time fetching of the current date.

5. new Date(numbers):

   • Benchmark Definition: date = new Date(2024, 1, 1);
   • Description: This test creates a date using separate year, month, and day parameters.
   • Pros: Provides clarity on creating specific dates without needing a string representation. Month is zero-indexed (0 for January).
   • Cons: May introduce potential confusion due to the zero-based month index, leading to off-by-one errors.

Performance Results

The results from the latest benchmark indicate the following ExecutionsPerSecond for each test case:

• new Date(number): 10,610,037
• new Date(): 9,117,674
• new Date(short string): 7,502,250.5
• new Date(full string): 5,501,832
• new Date(numbers): 4,751,458

Observations

• Numeric Input Efficiency: The performance of the numeric input test (new Date(number)) significantly outperforms the others, confirming that using timestamps is generally the most efficient for date creation.
• Impact of String Parsing: As shown by the slower performance of the string-based tests (full string and short string), parsing date strings can be computationally more expensive.
• Usage Context: The choice of which method to use often depends on the context:
  • Numeric inputs are ideal for performance-critical applications.
  • String inputs are useful when dealing with human-readable date representations, despite the cost in performance.

Alternatives

• Date Libraries: Tools like Moment.js or date-fns provide advanced date manipulation features and often simplify working with dates, but they may incur overhead compared to basic Date usage. However, they also handle edge cases effectively, which can be helpful in robust applications.
• Temporal API: The upcoming ECMAScript Temporal API aims to improve the built-in date and time handling in JavaScript, providing a modern interface for dealing with dates that may offer better performance and usability than the current Date object.

In summary, this benchmark provides crucial insights into the performance implications of various methods for creating Date objects in JavaScript, helping developers choose the right approach based on their specific needs.