Benchmark: Date constructor performance

Script Preparation code:

let date;

Tests:

new Date(full string)
date = new Date('2023-09-18T16:29:10.093Z');
new Date(short string)
date = new Date('2023-09-18');
new Date(number)
date = new Date(1695054550093);
new Date()
date = new Date();
new Date(numbers)
date = new Date(2024, 1, 1);

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
new Date(full string)
new Date(short string)
new Date(number)
new Date()
new Date(numbers)

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 2 months ago)

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/133.0.0.0 Safari/537.36

Browser/OS: Chrome 133 on Mac OS X 10.15.7

View result in a separate tab

Test name	Executions per second
new Date(full string)	5501832.0 Ops/sec
new Date(short string)	7502250.5 Ops/sec
new Date(number)	10610037.0 Ops/sec
new Date()	9117674.0 Ops/sec
new Date(numbers)	4751458.0 Ops/sec

Autogenerated LLM Summary (model gpt-4o-mini, generated 2 months ago):

LLMs can make mistakes. Check important info.

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.

Related benchmarks:

Date constructor performance (version: 1)

Comparing the performance of different inputs to the Date constructor.

Comparing performance of: new Date(full string) vs new Date(short string) vs new Date(number) vs new Date() vs new Date(numbers)

Created: 2 months ago by: Registered User

Jump to the latest result

new Date(full string)

new Date(short string)

new Date(number)

new Date()

new Date(numbers)

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model gpt-4o-mini, generated 2 months ago):