Benchmark: new Date(date) vs new Date(normalizeToLocalDate(date)) 3

Script Preparation code:

var dateTimeISO = '2024-08-21T17:00:00.000Z'
var dateOnlyISO = '2024-08-21'

var normalizeToLocalDate = (date) =>
    date.length === 10 && /^\d{4}-\d{2}-\d{2}$/.test(date) ? ` ${date}` : date;

Tests:

new Date(dateTimeISO)
new Date(dateTimeISO)
new Date(normalizeToLocalDate(dateTimeISO))
new Date(normalizeToLocalDate(dateTimeISO))
new Date(dateOnlyISO)
new Date(dateOnlyISO)
new Date(normalizeToLocalDate(dateOnlyISO))
new Date(normalizeToLocalDate(dateOnlyISO))

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
new Date(dateTimeISO)
new Date(normalizeToLocalDate(dateTimeISO))
new Date(dateOnlyISO)
new Date(normalizeToLocalDate(dateOnlyISO))

Fastest: N/A

Slowest: N/A

Latest run results:

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

User agent: Mozilla/5.0 (Linux; Android 10; K) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/128.0.0.0 Mobile Safari/537.36

Browser/OS: Chrome Mobile 128 on Android

View result in a separate tab

Test name	Executions per second
new Date(dateTimeISO)	911994.1 Ops/sec
new Date(normalizeToLocalDate(dateTimeISO))	858043.6 Ops/sec
new Date(dateOnlyISO)	1095093.2 Ops/sec
new Date(normalizeToLocalDate(dateOnlyISO))	730371.9 Ops/sec

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

LLMs can make mistakes. Check important info.

I'll do my best to break down the provided JSON and explain what's being tested.

**Benchmark Definition**

The benchmark definition is testing four different ways of creating a new `Date` object:

1. Directly using the ISO date string (`new Date(dateTimeISO)`).
2. Normalizing an ISO date string to a local date format before passing it to `new Date()` (`new Date(normalizeToLocalDate(dateTimeISO))`).
3. Using only the year, month, and day components of an ISO date string (without hours, minutes, or seconds) without normalization (`new Date(dateOnlyISO)`).
4. Normalizing the year, month, and day components of an ISO date string to a local format before passing it to `new Date()` (`new Date(normalizeToLocalDate(dateOnlyISO))`).

**Options Compared**

The options being compared are:

* Directly using the full ISO date string.
* Normalizing the date string to a local format before passing it to `new Date()`.
* Using only the year, month, and day components of the ISO date string.

**Pros and Cons of Different Approaches**

1. **Directly using the full ISO date string**: This approach is simple and straightforward. However, it may not be efficient if the date string needs to be parsed and validated before being used.
2. **Normalizing the date string**: Normalizing the date string can improve performance by reducing the amount of work that `new Date()` needs to do. However, this approach requires additional code and may add complexity.
3. **Using only the year, month, and day components**: This approach is simpler than normalization but may not be as efficient or accurate, especially if the date string has a different format.

**Library Usage**

The benchmark uses a custom function `normalizeToLocalDate` which takes an ISO date string as input and returns a normalized local date string. The library used is not explicitly mentioned in the provided JSON, but it's likely that this function is using a combination of regular expressions and JavaScript's built-in Date parsing functionality.

**Special JS Features or Syntax**

There are no special JS features or syntax used in this benchmark. It only relies on basic JavaScript syntax for creating dates and comparing execution times.

**Alternatives**

Some alternative approaches to testing date creation benchmarks could include:

* Using a different method of creating dates, such as using `Date.now()` instead of `new Date()`.
* Testing the performance of different libraries or frameworks that support date parsing.
* Creating more complex date formats with varying levels of precision and complexity.

Overall, this benchmark is testing the efficiency of different approaches to creating new `Date` objects, specifically comparing direct usage of ISO date strings, normalization, and simplified date component extraction.

Related benchmarks:

new Date(date) vs new Date(normalizeToLocalDate(date)) 3 (version: 0)

Comparing performance of: new Date(dateTimeISO) vs new Date(normalizeToLocalDate(dateTimeISO)) vs new Date(dateOnlyISO) vs new Date(normalizeToLocalDate(dateOnlyISO))

Created: one year ago by: Registered User

Jump to the latest result

new Date(dateTimeISO)

new Date(normalizeToLocalDate(dateTimeISO))

new Date(dateOnlyISO)

new Date(normalizeToLocalDate(dateOnlyISO))

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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