Benchmark: Date vs Performance.now

HTML Preparation code:

<!--your preparation HTML code goes here-->

Script Preparation code:

/*your preparation JavaScript code goes here
To execute async code during the script preparation, wrap it as function globalMeasureThatScriptPrepareFunction, example:*/
async function globalMeasureThatScriptPrepareFunction() {
    // This function is optional, feel free to remove it.
    // await someThing();
}

Tests:

Performance.now
function testPerformanceNowSingle() { return performance.now(); }; testPerformanceNowSingle();
Date.now
function testDateNowSingle() { return Date.now(); }; testDateNowSingle();

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Performance.now
Date.now

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 23 days ago)

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/148.0.0.0 Safari/537.36

Browser/OS: Chrome 148 on Mac OS X 10.15.7

View result in a separate tab

Test name	Executions per second
Performance.now	8797310.0 Ops/sec
Date.now	26160788.0 Ops/sec

Autogenerated LLM Summary (model gpt-4o-mini, generated 10 months ago):

LLMs can make mistakes. Check important info.

The benchmark compares two approaches for measuring time in JavaScript: `Date.now()` and `performance.now()`. Each approach has its own characteristics and use cases.

### Approaches Compared

1. **`Date.now()`**
   - This method returns the current timestamp in milliseconds since January 1, 1970, 00:00:00 UTC.
   - Use Case: It is commonly used in general applications where simple time-based calculations or comparisons are needed.
   
2. **`performance.now()`**
   - This method returns a timestamp measured in milliseconds with sub-millisecond precision (i.e., fractions of a millisecond).
   - Use Case: It is particularly useful in performance-sensitive scenarios, such as animations, measurements of code execution time, or any timing scenarios where accuracy is crucial.

### Benchmark Results

In the provided benchmark results:
- `Date.now()` achieved approximately **35,281,896 executions per second**, while `performance.now()` achieved about **9,422,804 executions per second**.
- This shows that `Date.now()` is significantly faster in terms of sheer execution rate.

### Pros/Cons

**`Date.now()`**
- **Pros:**
  - Faster execution time.
  - Simplicity and ease of use.
- **Cons:**
  - Provides timestamps in whole milliseconds, which may not be precise enough for performance measurements in certain applications.

**`performance.now()`**
- **Pros:**
  - High precision (sub-millisecond).
  - Ideal for measuring short durations and profiling code performance.
- **Cons:**
  - Slower execution compared to `Date.now()`.
  - Might be overkill for simple time-stamping needs where millisecond precision is unnecessary.

### Other Considerations

- Use `Date.now()` when needing to obtain a simple timestamp or when the precision of a millisecond is adequate for your needs.
- Use `performance.now()` when timing fine-grained performance measurements, animations, or more complex time-related calculations where precision is key.

### Alternatives

Apart from `Date.now()` and `performance.now()`, other alternatives for measuring time in JavaScript include:

- **`setTimeout` and `setInterval`:** These functions can be used for timing events but are less reliable for performance measurement because their timing can be affected by other operations in the event loop.
  
- **`console.time()` and `console.timeEnd()`:** These methods allow you to measure performance between start and end markers. They internally use high-resolution timers.

- **`process.hrtime()`:** Available in Node.js, this function provides high-resolution real time in [seconds, nanoseconds]. It is particularly useful on the server-side for precise benchmarking.

### Conclusion

In summary, both `Date.now()` and `performance.now()` serve vital roles depending on the context of use. Choosing between them largely depends on the requirements for accuracy versus speed in time measurement. For performance benchmarking and critical timing scenarios, `performance.now()` is the better choice due to its precision, while `Date.now()` is suitable for general timestamping and performing simple operations that do not require high precision.

Related benchmarks:

Date vs Performance.now (version: 1)

Comparing performance of: Performance.now vs Date.now

Created: 10 months ago by: Guest

Jump to the latest result

Performance.now

Date.now

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model gpt-4o-mini, generated 10 months ago):