Benchmark: new Date from timestamp vs new Date from date-string

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Script Preparation code:

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async function globalMeasureThatScriptPrepareFunction() {
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Tests:

new timestamp
new Date(1745899511871)
new date-string
new Date("2025-04-29T04:05:11.870Z")

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
new timestamp
new date-string

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 16 hours ago)

User agent: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/135.0.0.0 Safari/537.36

Browser/OS: Chrome 135 on Linux

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Test name	Executions per second
new timestamp	20767956.0 Ops/sec
new date-string	3635966.8 Ops/sec

Autogenerated LLM Summary (model gpt-4o-mini, generated 15 hours ago):

LLMs can make mistakes. Check important info.

The benchmark you've provided tests two different approaches for creating a JavaScript `Date` object: one using a timestamp and the other using a date string. The benchmark compares the performance of these two methods by measuring how many times each can be executed in one second.

### Test Cases

1. **Test Case: new timestamp**
   - **Benchmark Definition**: `new Date(1745899511871)`
   - **Test Name**: `new timestamp`
   - **Description**: This test creates a `Date` object using a numeric timestamp (milliseconds since the Unix epoch).

2. **Test Case: new date-string**
   - **Benchmark Definition**: `new Date("2025-04-29T04:05:11.870Z")`
   - **Test Name**: `new date-string`
   - **Description**: This test creates a `Date` object by passing a date string formatted as an ISO 8601 date string.

### Performance Results

From the benchmark results:
- The `new timestamp` approach achieved **20,767,956.0** executions per second.
- The `new date-string` approach achieved **3,635,966.75** executions per second.

### Comparison of Approaches

#### Pros and Cons

1. **Using Timestamp (`new Date(timestamp)`)**:
   - **Pros**: 
     - Generally faster, as evidenced by the benchmark results. This approach bypasses any parsing logic and directly uses the numeric value.
     - Simple and straightforward for situations where you already have the timestamp.
   - **Cons**:
     - Not human-readable. If the goal is to communicate or log a date, a numeric timestamp is less informative.

2. **Using Date String (`new Date("date-string")`)**:
   - **Pros**:
     - More readable and easier to understand at a glance. This is particularly useful for setting or logging dates in a way that is meaningful to humans.
     - Can include timezone information if specified correctly (though that may add overhead in parsing).
   - **Cons**:
     - Slower performance due to the need to parse the string into a date object. This overhead can be significant, especially in performance-sensitive applications.
     - Potential issues with date strings that are not in the expected format, leading to incorrect Date objects.

### Other Considerations

- **Timezones**: When using date strings, developers must be cautious about timezones, as date strings without explicit timezone information may be interpreted differently based on the system's local timezone settings.
  
- **Legacy Compatibility**: Older browser versions may handle date string parsing inconsistently, particularly with formats other than ISO 8601. Using timestamps ensures greater compatibility across different browsers.

### Alternatives

Other options for creating `Date` objects in JavaScript can include:

- **Moment.js**: Although now considered a legacy library, it provides a powerful API for parsing, manipulating, and displaying dates. It has its overhead due to additional functionalities and is typically slower than native JavaScript methods.
  
- **Date-fns**: A modern library with a modular approach, allowing developers to import only the functions they need, potentially offering better performance than Moment.js.

- **Luxon**: A library built on the native `Intl` API, providing time zone support and a more modern API. It may be slower than the native `Date` methods but excels in handling complex date manipulations.

### Conclusion

In summary, the benchmark tests the performance difference between creating `Date` instances using a numeric timestamp versus a date string. The timestamp approach is generally faster and more efficient, while the date string approach is more human-readable but incurs a performance penalty due to additional parsing requirements. When choosing between these methods, the specific use case and performance requirements should guide the decision.

Related benchmarks:

new Date from timestamp vs new Date from date-string (version: 1)

Comparing performance of: new timestamp vs new date-string

Created: 16 hours ago by: Guest

Jump to the latest result

new timestamp

new date-string

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model gpt-4o-mini, generated 15 hours ago):