Benchmark: in getDay vs array

Script Preparation code:

var date = new Date();

function toISOString(date) {
	['Sunday','Monday','Tuesday','Wednesday', 'Thursday','Friday','Saturday'][date.getDay()]
}

var arr = ['Sunday','Monday','Tuesday','Wednesday', 'Thursday','Friday','Saturday'];
function concat(date) {
 	arr[date.getDay()];
}

Tests:

toISOString
for (var i=0; i<1000; ++i) { toISOString(date); }
concat
for (var i=0; i<1000; ++i) { concat(date); }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
toISOString
concat

Fastest: N/A

Slowest: N/A

Latest run results:

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

LLMs can make mistakes. Check important info.

I'd be happy to explain what's being tested in this benchmark and the different approaches compared.

**Benchmark Definition**

The provided JSON represents a JavaScript microbenchmarking test case, specifically comparing two functions: `toISOString` and `concat`. These functions are used to extract the day of the week from a date object.

Here's a breakdown of the `Script Preparation Code`:

* The script creates a new `Date` object called `date`.
* It defines an array `arr` containing the days of the week.
* Two functions are defined: `toISOString(date)` and `concat(date)`. Both functions take the `date` parameter, but they use it differently:
	+ `toISOString(date)` uses the day of the week index from the `date` object as an array index to retrieve the corresponding day from the `arr` array.
	+ `concat(date)` also uses the day of the week index from the `date` object as an array index, but simply returns the value at that index without any additional processing.

**Options Compared**

The benchmark is comparing two approaches:

1. **Direct Array Access**: This approach uses the `toISOString(date)` function to access the day of the week by index.
2. **Array Concatenation**: This approach uses the `concat(date)` function to concatenate the day of the week as a string.

**Pros and Cons**

* **Direct Array Access (toISOString)**:
	+ Pros: Can be more efficient if the array is large, as it avoids unnecessary concatenation or copying.
	+ Cons: Requires explicit array indexing, which can be slower due to cache misses.
* **Array Concatenation (concat)**:
	+ Pros: Simplifies code and avoids explicit array indexing, which can lead to faster execution times.
	+ Cons: May incur additional overhead from string concatenation or memory allocation.

**Library Use**

The `toISOString` function uses the Array index syntax (`arr[date.getDay()]`) without explicitly importing any library. However, this syntax is specific to JavaScript's `getDay()` method, which returns a value between 0 (Sunday) and 6 (Saturday). This value can be used as an array index in most modern browsers.

**Special JS Feature or Syntax**

The benchmark uses the `getDay()` method on the `Date` object to extract the day of the week. This is not a special feature, but rather a built-in property of the `Date` object in JavaScript.

**Other Alternatives**

There are other ways to achieve similar results without using these specific functions:

* Direct array access with an object index (e.g., `arr[date.getDay()]` could be replaced with `obj[date.getDay()]`, where `obj` is another object containing day of the week strings).
* Using a lookup table or an object to map day numbers to their corresponding names.
* Utilizing modern JavaScript features like destructuring assignment or arrow functions.

Keep in mind that the choice of approach often depends on the specific requirements and constraints of the project, as well as personal preference.

Related benchmarks:

in getDay vs array (version: 0)

Comparing performance of: toISOString vs concat

Created: 4 years ago by: Guest

Jump to the latest result

toISOString

concat

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

No previous run results

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