Benchmark: new Date from string vs new Date from number timestamp

Tests:

new Date from string
new Date('2025-04-07T16:04:30.229Z');
new Date from number timestamp
new Date(1744041883220);

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
new Date from string
new Date from number timestamp

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 22 days ago)

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/134.0.0.0 Safari/537.36 Edg/134.0.0.0

Browser/OS: Chrome 134 on Windows

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Test name	Executions per second
new Date from string	5286221.5 Ops/sec
new Date from number timestamp	29260726.0 Ops/sec

Autogenerated LLM Summary (model gpt-4o-mini, generated 22 days ago):

LLMs can make mistakes. Check important info.

In this benchmark test, we are comparing two different methods of creating a JavaScript `Date` object: one from a string and the other from a number timestamp. Here's a detailed analysis of what is tested and the implications of each approach.

### Benchmark Overview

#### Options Compared
1. **Creating a Date from a String**:
   - **Benchmark Definition**: `new Date('2025-04-07T16:04:30.229Z');`
   - This method utilizes an ISO 8601 formatted date string to instantiate a `Date` object.

2. **Creating a Date from a Number Timestamp**:
   - **Benchmark Definition**: `new Date(1744041883220);`
   - In this case, a numeric value representing the number of milliseconds elapsed since the Unix epoch (January 1, 1970) is used to create the `Date` object.

### Performance Results
According to the benchmark results, the execution rates for these methods were as follows:
- **`new Date from number timestamp`**: 29,260,726 executions per second.
- **`new Date from string`**: 5,286,221.5 executions per second.

### Pros and Cons

#### `new Date from String`
- **Pros**:
  - **Readability**: The string representation is often more understandable and easier to read for humans. This can be very useful for debugging or logging purposes.
  - **Flexibility**: Supports various formats (if handled correctly), allowing for easy parsing of human-readable dates.

- **Cons**:
  - **Performance**: As indicated by the benchmark results, this method is significantly slower than the numeric timestamp approach. Parsing the string adds overhead.
  - **Risk of Errors**: If the date string is not formatted correctly, it can lead to errors or unexpected results, which may require additional validation logic.

#### `new Date from Number Timestamp`
- **Pros**:
  - **Performance**: This approach is faster, as shown in the benchmark results, because it involves a direct numeric conversion without additional parsing.
  - **Precision**: Using timestamps reduces the likelihood of errors related to format since it is a straightforward numeric value.

- **Cons**:
  - **Less Readable**: Timestamps are not as human-readable as date strings, making them harder to interpret without conversion.
  - **Configuration**: Developers must ensure that the correct timestamp is used, which may involve additional logic to convert dates to timestamps in certain situations.

### Other Considerations
- The choice between these two methods should be guided by the specific use case. For applications where performance is critical and many date objects are created in a loop, the timestamp approach is preferable. Conversely, for applications where dates are displayed or logged for human interaction, using string representation might be beneficial despite the performance hit.
  
- Developers may also explore libraries such as [Moment.js](https://momentjs.com/) (though now considered legacy) or [date-fns](https://date-fns.org/) for more complex date manipulations. These libraries often provide better parsing capabilities, ease the handling of time zones, and improve overall date handling in JavaScript applications.

- Additionally, the introduction of the `Intl.DateTimeFormat` API and the `Temporal` API in modern JavaScript offers even richer features for date and time manipulation, which could be considered as alternatives in future developments.

In summary, this benchmark effectively highlights the performance differences between two common methods of instantiating `Date` objects in JavaScript and provides insightful considerations for developers faced with similar use cases.

Related benchmarks:

new Date from string vs new Date from number timestamp (version: 1)

Comparing performance of: new Date from string vs new Date from number timestamp

Created: 22 days ago by: Guest

Jump to the latest result

new Date from string

new Date from number timestamp

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model gpt-4o-mini, generated 22 days ago):