Benchmark: new Intl.DateTimeFormat vs new Date().toLocaleDateString() take 2

Script Preparation code:

var options = {
  year: 'numeric', month: 'numeric', day: 'numeric',
  hour: 'numeric', minute: 'numeric', second: 'numeric',
  hour12: false,
  fractionalSecondDigits: 3,
}

Tests:

new Date()
(new Date()).toISOString().trim().replace('T', ' ').replace('Z', '')
Intl.DateTimeFormat()
new Intl.DateTimeFormat('en-US', options).format(new Date())
Date().toLocaleDateString()
new Date().toLocaleDateString("en-US", options)
JavaScript Date Time format
let date_time = new Date() let formatted_date = date_time.getFullYear() + "-" + (date_time.getMonth() + 1) + "-" + date_time.getDate() + " " + date_time.getHours() + ":" + date_time.getMinutes() + ":" + date_time.getSeconds() + "." + date_time.getMilliseconds()
JavaScript Date Time format using Template Strings.
let date_time = new Date() let formatted_date = `${date_time.getFullYear()}-${date_time.getMonth() + 1}-${date_time.getDate()} ${date_time.getHours()}:${date_time.getMinutes()}:${date_time.getSeconds()}.${date_time.getMilliseconds()}`

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
new Date()
Intl.DateTimeFormat()
Date().toLocaleDateString()
JavaScript Date Time format
JavaScript Date Time format using Template Strings.

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/111.0.0.0 Safari/537.36

Browser/OS: Chrome 111 on Mac OS X 10.15.7

View result in a separate tab

Test name	Executions per second
new Date()	734842.7 Ops/sec
Intl.DateTimeFormat()	7696.3 Ops/sec
Date().toLocaleDateString()	7740.3 Ops/sec
JavaScript Date Time format	1589868.8 Ops/sec
JavaScript Date Time format using Template Strings.	1602839.4 Ops/sec

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

LLMs can make mistakes. Check important info.

Let's break down the provided benchmark and explain what is being tested.

**Benchmark Definition**

The benchmark measures the performance of three different approaches to format dates in JavaScript:

1. `new Date()` followed by string manipulation
2. `Intl.DateTimeFormat()` with options
3. `Date().toLocaleDateString()`
4. A custom implementation using template strings (JavaScript 2015+ syntax)
5. Another custom implementation without using template strings

**Comparison of Approaches**

The benchmark compares the performance of these five approaches, which can be categorized into two main groups:

* **Native JavaScript APIs**: `new Date()` and `Date().toLocaleDateString()`
	+ Pros:
		- Native to JavaScript and widely supported
		- Typically faster due to being implemented in native code
	+ Cons:
		- Less flexible than other approaches (e.g., limited options for formatting)
* **Built-in API with Options**: `Intl.DateTimeFormat()` with options
	+ Pros:
		- Highly customizable
		- Can produce more accurate and localized date representations
	+ Cons:
		- May be slower due to additional overhead from the internationalization library
* **Custom Implementations**:
	+ Template Strings (JavaScript 2015+ syntax)
	+ Without template strings

The pros and cons of each approach are as follows:

* `new Date()` and `Date().toLocaleDateString()`: Fast, but limited flexibility.
* `Intl.DateTimeFormat()` with options: Highly customizable, but may be slower.
* Custom implementations using template strings: Flexible, but may incur overhead due to syntax parsing. Without template strings, the implementation is less flexible and may have additional runtime overhead.

**Library: Intl.DateTimeFormat()**

`Intl.DateTimeFormat()` is a built-in JavaScript API for formatting dates according to the rules of different languages and regions. It provides a way to create date representations that are culturally sensitive and accurate. The options object passed to `Intl.DateTimeFormat()` allows for fine-grained control over the formatting, such as specifying the year, month, day, hour, minute, second, and fractional second digits.

**Special JS Feature/Syntax**

The benchmark uses template strings (JavaScript 2015+ syntax), which are a feature that allows embedding expressions inside string literals. This is used in two of the custom implementations: `let formatted_date = ${date_time.getFullYear()}-${date_time.getMonth() + 1}-${date_time.getDate()} ...`. The `${}` notation indicates where the expression should be evaluated and inserted into the string.

**Alternatives**

Other alternatives for formatting dates in JavaScript include:

* Using external libraries like Moment.js or Luxon, which provide a wide range of date formatting options and are often faster than native JavaScript APIs.
* Using third-party date formatting libraries that can be integrated with existing codebases.
* Implementing custom date formatting using low-level browser APIs or native JavaScript methods.

Overall, the benchmark highlights the trade-offs between different approaches to date formatting in JavaScript: speed, flexibility, and accuracy.

Related benchmarks:

new Intl.DateTimeFormat vs new Date().toLocaleDateString() take 2 (version: 0)

Comparing performance of: new Date() vs Intl.DateTimeFormat() vs Date().toLocaleDateString() vs JavaScript Date Time format vs JavaScript Date Time format using Template Strings.

Created: one year ago by: Guest

Jump to the latest result

new Date()

Intl.DateTimeFormat()

Date().toLocaleDateString()

JavaScript Date Time format

JavaScript Date Time format using Template Strings.

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):