Benchmark: Create Date - MeasureThat.net

Script Preparation code:

var start = new Date();
var temp1 = new Date();

Tests:

New
var new1 = new Date(start) new1.setHours(0,0,0,0); new1 = new1.getTime();
Reuse
temp1.setTime(start.getTime()); temp1.setHours(0,0,0,0); var new1 = temp1.getTime();

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
New
Reuse

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated one month ago):

LLMs can make mistakes. Check important info.

**Overview of the Benchmark**

The provided JSON represents a JavaScript microbenchmark, specifically measuring the performance difference between two approaches: creating a new Date object and reusing an existing one.

**Script Preparation Code**

The script preparation code is identical for both test cases:
```javascript
var start = new Date();
```
This line creates a new Date object, storing its timestamp in the `start` variable. This serves as a reference point for subsequent operations.

**Html Preparation Code**

There is no HTML preparation code provided, which means that only JavaScript performance is being measured and compared.

**Test Cases**

There are two test cases:

1. **New**: This approach creates a new Date object using the `new Date()` constructor and then sets its hour, minute, second, and millisecond values to zero. Finally, it extracts the timestamp from the Date object using the `getTime()` method.
```javascript
var new1 = new Date(start)
  .setHours(0, 0, 0, 0);
new1 = new1.getTime();
```
2. **Reuse**: This approach creates a temporary Date object (`temp1`) using the `new Date()` constructor and stores its initial timestamp in the `start` variable. It then sets the hour, minute, second, and millisecond values of the Date object to zero using the `setTime()` method. Finally, it extracts the updated timestamp from the Date object using the `getTime()` method.
```javascript
var temp1 = new Date(start);
temp1.setTime(start.getTime());
temp1.setHours(0, 0, 0, 0);
var new1 = temp1.getTime();
```
**Pros and Cons of Each Approach**

1. **New**:
	* Pros: Creates a new object, which might be faster for some browsers (see below).
	* Cons: Creates an additional temporary object (`new1`) that needs to be stored in memory.
2. **Reuse**:
	* Pros: Reuses the existing `temp1` object, reducing memory allocation and deallocation overhead.
	* Cons: Requires setting the Date object's values using the `setTime()` method, which might introduce additional overhead.

**Browser Behavior**

The benchmark results indicate that different browsers exhibit varying behavior:

* **Chrome 53**: In this browser, creating a new Date object (`New`) is approximately twice as fast as reusing an existing one (`Reuse`).
* **Other Browsers**: The performance difference between `New` and `Reuse` seems to be less pronounced in other browsers.

**Library Usage**

The benchmark does not explicitly use any JavaScript libraries. However, the Date object itself has some internal complexities that might affect performance, such as:

* **Milliseconds**: The Date object's millisecond resolution is affected by the system clock's precision.
* **JavaScript engines' optimizations**: Modern JavaScript engines like V8 (used in Chrome) and SpiderMonkey (used in Firefox) perform various optimizations on the Date object to improve performance.

**Special JS Feature or Syntax**

There are no special features or syntax used in this benchmark. The code is straightforward JavaScript that leverages built-in Date object methods.

**Alternatives**

Other alternatives for measuring performance differences between creating a new Date object and reusing an existing one might include:

* Using the `performance.now()` function, which returns the current time in milliseconds without any additional overhead.
* Creating a custom benchmarking framework using tools like WebPageTest or Benchmark.js.

Latest run results:

Run details: (Test run date: 8 years ago)

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_10_3) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/53.0.2785.116 Safari/537.36

Browser/OS: Chrome 53 on Mac OS X 10.10.3

View result in a separate tab

Test name	Executions per second
New	1938688.6 Ops/sec
Reuse	1853102.9 Ops/sec

Related benchmarks:

Create Date (version: 0)

Comparing performance of: New vs Reuse

Created: 8 years ago by: Guest

Jump to the latest result

New

Reuse

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated one month ago):