Benchmark: filter-foreach vs foreach+if

Script Preparation code:

var arr = [];
for (var i = 0; i < 12345; i++) {
  arr[i] = i;
}

Tests:

filter + foreach
const filtered = arr.filter(i => i > 6172); filtered.forEach(i => i++); const count = filtered.length;
foreach + if
let count = 0; arr.forEach(i => { if (i > 6172) { count++; i++; } });

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
filter + foreach
foreach + if

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_11_6) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/103.0.0.0 Safari/537.36

Browser/OS: Chrome 103 on Mac OS X 10.11.6

View result in a separate tab

Test name	Executions per second
filter + foreach	2191.9 Ops/sec
foreach + if	10382.3 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's being tested, compared, and their pros and cons.

**Benchmark Definition**

The website `MeasureThat.net` provides a JSON definition for a benchmark. In this case:

* The name of the benchmark is "filter-foreach vs foreach+if".
* The description is null.
* The script preparation code creates an array `arr` with 12345 elements, initialized with values from 0 to 12344.

**Test Cases**

There are two individual test cases:

1. **"filter + foreach"**: This test case uses the `Array.prototype.filter()` method and then iterates over the resulting array using `Array.prototype.forEach()`. The iteration also increments each element in the array.
2. **"foreach + if"**: This test case uses `Array.prototype.forEach()` to iterate over the original array, but instead of incrementing each element directly, it checks if each element is greater than 6172 (a hardcoded value) and increments a separate variable `count` only when this condition is true.

**Options Compared**

In essence, these two test cases compare:

* Using the `Array.prototype.filter()` method followed by iterating over the resulting array (`filter + foreach`) versus
* Iterating directly over the original array using `Array.prototype.forEach()` and performing the increment operation within the callback function (`foreach + if`).

**Pros and Cons**

1. **"filter + foreach"`:
	* Pros:
		+ This approach can be more readable, as it separates the filtering from the iteration.
		+ It might produce fewer false positives (i.e., elements that are not greater than 6172 being considered as such).
	* Cons:
		+ Creating a new array using `Array.prototype.filter()` can lead to memory allocation overhead and potentially slower performance for large arrays.
		+ The iteration may not be more efficient due to the additional step of creating an intermediate array.
2. **"foreach + if"`:
	* Pros:
		+ This approach does not require any extra memory allocations, as it only iterates over the original array.
	* Cons:
		+ It can lead to more complex code, making it harder to read and maintain.
		+ The condition `i > 6172` needs to be checked for each element in the array, potentially leading to more iterations.

**Library Usage**

There is no explicit library mentioned in this benchmark. However, JavaScript's built-in array methods like `Array.prototype.filter()` and `Array.prototype.forEach()` are used.

**Special JS Feature/Syntax**

No special JavaScript features or syntax are used in these test cases. The code only employs standard JavaScript constructs.

**Alternatives**

If you wanted to write similar benchmarks for other iterations (e.g., using `map()`, `reduce()`, or more advanced array methods), you could explore using different methods and analyze their performance characteristics, trade-offs, and potential improvements.

Related benchmarks:

filter-foreach vs foreach+if (version: 0)

Comparing performance of: filter + foreach vs foreach + if

Created: one year ago by: Guest

Jump to the latest result

filter + foreach

foreach + if

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):