Benchmark: Cached vs new Intl.DateTimeFormat

Script Preparation code:

const TWO_DIGIT = '2-digit';

var options = {
      month: TWO_DIGIT,
      year: 'numeric',
      day: TWO_DIGIT,
      hour: TWO_DIGIT,
      hour12: false,
      minute: TWO_DIGIT,
      second: TWO_DIGIT,
    }

var cached = new Intl.DateTimeFormat('en-US', options);
var date = new Date();
var number = date.getTime();

Tests:

new Intl.DateTimeFormat.format(date)
new Intl.DateTimeFormat('en-US', options).format(date);
cached Intl.DateTimeFormat.format(date)
cached.format(date);
new Intl.DateTimeFormat.format(number)
new Intl.DateTimeFormat('en-US', options).format(number);
cached Intl.DateTimeFormat.format(number)
cached.format(number);

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
new Intl.DateTimeFormat.format(date)
cached Intl.DateTimeFormat.format(date)
new Intl.DateTimeFormat.format(number)
cached Intl.DateTimeFormat.format(number)

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 26 days ago):

LLMs can make mistakes. Check important info.

Let's dive into the benchmark.

The provided JSON represents a JavaScript microbenchmark that compares two approaches to formatting dates with the `Intl.DateTimeFormat` API:

1. **Caching**: Creating an instance of `Intl.DateTimeFormat` once and reusing it throughout the test cases.
2. **New instance every time**: Creating a new instance of `Intl.DateTimeFormat` for each test case.

**Library:**
`Intl.DateTimeFormat` is a part of the JavaScript Internationalization API, which provides functions for formatting dates, times, and numbers according to the conventions of different languages and regions.

**Purpose:**
The purpose of this benchmark is to measure the performance impact of caching versus creating a new instance of `Intl.DateTimeFormat` for each test case. The idea behind caching is that by reusing the same instance, you can avoid the overhead of creating a new object every time, which can lead to significant performance improvements.

**Options:**
The options being compared are:

* `month`, `year`, `day`, `hour`, `hour12`, `minute`, and `second` formats.
* The `format` method is used to format dates and numbers.

**Pros and Cons of each approach:**

1. **Caching**:
	* Pros:
		+ Reusing the same instance can lead to performance improvements due to reduced object creation overhead.
		+ Simplifies code by avoiding the need to create a new instance for each test case.
	* Cons:
		+ May not be suitable if the options change frequently between test cases, as the cached instance may become outdated.
2. **New instance every time**:
	* Pros:
		+ Allows for more flexibility and control over formatting options, as each instance can have a different set of options.
	* Cons:
		+ Can lead to performance overhead due to object creation, especially if many instances are created.

**Special JS feature or syntax:**
The benchmark uses the `const` keyword to declare variables, which is a modern JavaScript feature that helps improve code readability and maintainability. It also uses arrow functions (`() => {...}`) for simplicity, which is another modern JavaScript feature.

**Other alternatives:**

* Instead of using caching, you could use a technique called " lazy initialization," where the instance is created only when needed.
* Another approach would be to use a different library or implementation that optimizes performance in this specific scenario.

In terms of actual implementation, the script preparation code creates an instance of `Intl.DateTimeFormat` with the specified options and stores it in a variable named `cached`. The HTML preparation code is empty, which means there's no additional setup required for the benchmark. The test cases define four different scenarios:

1. Creating a new instance of `Intl.DateTimeFormat` and formatting a date.
2. Caching an instance of `Intl.DateTimeFormat` and formatting a date.
3. Creating a new instance of `Intl.DateTimeFormat` and formatting a number.
4. Caching an instance of `Intl.DateTimeFormat` and formatting a number.

The benchmark results show the number of executions per second for each test case, which indicates the performance difference between caching and creating a new instance every time.

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/114.0.0.0 Safari/537.36

Browser/OS: Chrome 114 on Mac OS X 10.15.7

View result in a separate tab

Test name	Executions per second
new Intl.DateTimeFormat.format(date)	9200.6 Ops/sec
cached Intl.DateTimeFormat.format(date)	360932.4 Ops/sec
new Intl.DateTimeFormat.format(number)	9271.0 Ops/sec
cached Intl.DateTimeFormat.format(number)	388306.3 Ops/sec

Related benchmarks:

Cached vs new Intl.DateTimeFormat (version: 0)

measure the perf impact of caching calls to new Intl.DateTimeFormat

Comparing performance of: new Intl.DateTimeFormat.format(date) vs cached Intl.DateTimeFormat.format(date) vs new Intl.DateTimeFormat.format(number) vs cached Intl.DateTimeFormat.format(number)

Created: one year ago by: Guest

Jump to the latest result

new Intl.DateTimeFormat.format(date)

cached Intl.DateTimeFormat.format(date)

new Intl.DateTimeFormat.format(number)

cached Intl.DateTimeFormat.format(number)

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 26 days ago):