Benchmark: toLocalDateString vs Array index

Script Preparation code:

var date1 = new Date('5/09/2019');
var abbrMonthsOfYear = ['Jan', 'Feb', 'Mar', 'Apr', 'May', 'Jun', 'Jul', 'Aug', 'Sep', 'Oct', 'Nov', 'Dec'];

Tests:

with toLocaleDateString with regex replace
date1.toLocaleDateString('en', {month:'short'}).replace(/\u200E/g, '');
Get abbreviated month from array
abbrMonthsOfYear[date1.getMonth()];

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
with toLocaleDateString with regex replace
Get abbreviated month from array

Fastest: N/A

Slowest: N/A

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

LLMs can make mistakes. Check important info.

I'd be happy to explain what's being tested in the provided benchmark.

**Overview**

The benchmark measures the performance of two different approaches: using the `toLocaleDateString` method with a regular expression replacement, and accessing an element in an array based on its index (in this case, the abbreviated month from the previous date).

**Options compared**

There are two options being compared:

1. **Using `toLocaleDateString` with regex replacement**: This approach uses the `toLocaleDateString` method to format the date string, followed by replacing any Unicode character (`\\u200E`) with an empty string using a regular expression.
2. **Accessing an element in an array based on its index**: In this case, the abbreviated month is accessed from an array (`abbrMonthsOfYear`) using the `getMonth()` method of the date object (`date1`).

**Pros and Cons**

Here are some pros and cons of each approach:

* **Using `toLocaleDateString` with regex replacement**:
	+ Pros: This approach provides more control over the formatting of the date string, including handling non-English months.
	+ Cons: It requires using a regular expression, which can be slower than direct array access. Additionally, it may not work correctly for all locales or date formats.
* **Accessing an element in an array based on its index**:
	+ Pros: This approach is simple and straightforward, with faster execution times since it doesn't involve formatting or regex operations.
	+ Cons: It relies on the specific array structure and data, which may not be universally applicable.

**Library**

In this benchmark, no external libraries are explicitly mentioned. However, `Intl.DateTimeFormat` (not explicitly used here) could have been utilized for date format handling, but it is likely that was skipped or intentionally avoided in order to test pure JavaScript code execution performance.

**Special JS feature/syntax**

There's a notable mention of the 'short' option used for the month abbreviation with `toLocaleDateString`. In modern JavaScript environments (ECMAScript 2019 and above), you can use the `en` locale option along with specifying an option like `month: 'short'`, to format date strings more robustly.

Latest run results:

Run details: (Test run date: 4 years ago)

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/86.0.4240.198 Safari/537.36

Browser/OS: Chrome 86 on Windows

View result in a separate tab

Test name	Executions per second
with toLocaleDateString with regex replace	10844.4 Ops/sec
Get abbreviated month from array	5639091.5 Ops/sec

Related benchmarks:

toLocalDateString vs Array index (version: 0)

Checking the performance of a date toLocaleDateString

Comparing performance of: with toLocaleDateString with regex replace vs Get abbreviated month from array

Created: 5 years ago by: Registered User

Jump to the latest result

with toLocaleDateString with regex replace

Get abbreviated month from array

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):