Benchmark: Date.now() - Date.now() vs new Date() - new Date()

Script Preparation code:

var timedif = null;

Tests:

Date.now()
timedif = Date.now() - Date.now();
new Date().getTime();
timedif = new Date() - new Date();

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Date.now()
new Date().getTime();

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: one year ago)

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/108.0.0.0 Safari/537.36

Browser/OS: Chrome 108 on Mac OS X 10.15.7

View result in a separate tab

Test name	Executions per second
Date.now()	3120973.5 Ops/sec
new Date().getTime();	2333698.2 Ops/sec

Autogenerated LLM Summary (model llama3.1:latest, generated 2 months ago):

LLMs can make mistakes. Check important info.

Let's dive into what this benchmark is testing.

**Benchmark Definition**

The benchmark is called "Date.now() - Date.now() vs new Date() - new Date()" and it's comparing the performance of two approaches to measure time differences using JavaScript's built-in `Date` object.

**Individual Test Cases**

There are two test cases:

1. **"Date.now()"**
	* Benchmark Definition: `timedif = Date.now() - Date.now();`
	* This test case measures the time difference by subtracting the current timestamp (`Date.now()`) from itself.
2. **"new Date().getTime()"**
	* Benchmark Definition: `timedif = new Date() - new Date();`
	* This test case measures the time difference by creating two separate `Date` objects using `new Date()` and then subtracting their respective timestamps.

**Library/Feature Used**

In this benchmark, the only library or feature used is JavaScript's built-in `Date` object. There are no external libraries or special syntax involved.

**Pros/Cons of Different Approaches**

The two approaches being compared have different characteristics:

1. **"Date.now()"**
	* Pros:
		+ Simpler and more concise code
		+ Only involves a single function call (`Date.now()`)
	* Cons:
		+ May be less accurate due to the nature of subtracting identical values
2. **"new Date().getTime()"**
	* Pros:
		+ More accurate measurement, as it creates two separate `Date` objects with distinct timestamps
	* Cons:
		+ Slightly more complex code, involving two function calls (`new Date()`)

**Other Considerations**

When choosing between these approaches, consider the specific use case:

* If you need a quick and simple way to measure time differences for debugging or logging purposes, using `Date.now() - Date.now()` might be sufficient.
* For more accurate measurements or when precision matters (e.g., in performance-critical code), using `new Date().getTime() - new Date().getTime()` is generally recommended.

**Other Alternatives**

If you need to measure time differences with even higher accuracy, you may want to consider using:

1. **High-Resolution Timers**: Some browsers and platforms provide high-resolution timers that can offer more precise measurements than the built-in `Date` object.
2. **External Libraries**: Depending on your specific use case, external libraries like `performance-now` or `high-res-timer` might provide additional features and accuracy.

Overall, this benchmark provides a simple yet effective way to compare two common approaches for measuring time differences in JavaScript, helping developers make informed decisions about which approach best suits their needs.

Related benchmarks:

Date.now() - Date.now() vs new Date() - new Date() (version: 0)

Comparing performance of: Date.now() vs new Date().getTime();

Created: one year ago by: Guest

Jump to the latest result

Date.now()

new Date().getTime();

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.1:latest, generated 2 months ago):