Benchmark: filter(_ => _) vs filter(Boolean)

HTML Preparation code:

<script type="text/javascript" src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.15/lodash.min.js"></script>

Script Preparation code:

var elements = [0, 1, false, 2, '', 3];

Tests:

filter(_ => _)
elements.filter(_ => _)
filter(Boolean)
elements.filter(Boolean)

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
filter(_ => _)
filter(Boolean)

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 26 days ago):

LLMs can make mistakes. Check important info.

Let's break down the provided benchmark definition and test cases to understand what is being tested.

**What is being tested?**

The benchmark measures the performance difference between two approaches: filtering an array using an anonymous function (`_ => _`) versus using `Boolean`. The focus is on understanding how JavaScript engines optimize these operations.

**Options compared:**

1. **filter(_ => _)**: This approach uses a callback function (an anonymous function that takes one argument) as the predicate to filter elements from the `elements` array.
2. **filter(Boolean)**: This approach uses the built-in `Boolean` value as the predicate, effectively filtering out falsy values (including `false`, `0`, `undefined`, `null`, and empty strings) from the `elements` array.

**Pros and cons of each approach:**

1. **filter(_ => _)**:
	* Pros:
		+ Allows for more flexibility in defining the filter condition.
		+ Can be used with custom predicates.
	* Cons:
		+ May incur additional overhead due to the anonymous function creation.
2. **filter(Boolean)**:
	* Pros:
		+ Optimized for filtering out falsy values, which is a common use case.
		+ Typically faster than using an anonymous function.
	* Cons:
		+ Limited flexibility in defining the filter condition.

**Library and purpose:**

The benchmark includes a reference to Lodash.js, a popular JavaScript utility library. The `filter` function from Lodash is used as the implementation for both test cases.

**Special JS feature or syntax:**

There is no explicit mention of any special JavaScript features or syntax being tested in this benchmark. However, it's worth noting that some modern JavaScript engines (like V8) have optimized `Boolean` comparisons to be faster than using an anonymous function as a predicate.

**Other alternatives:**

If you wanted to test alternative approaches for filtering arrays, here are a few examples:

1. **Array.prototype.filter() without a predicate**: You can use the `filter()` method directly on the array without providing a predicate.
2. **map() and reduce() combination**: Instead of using `filter()`, you could use `map()` to create a new array with filtered elements and then use `reduce()` to flatten the resulting array.

Here's an example of how you might test these alternatives:
```json
{
    "Name": "filter(map/reduce)",
    "Description": null,
    "Script Preparation Code": "var elements = [0, 1, false, 2, '', 3];",
    "Html Preparation Code": "<script type=\"text/javascript\" src=\"https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.15/lodash.min.js\"></script>"
}

[
    {
        "Benchmark Definition": "elements.map(_ => _).reduce((a, b) => a.concat(b))",
        "Test Name": "filter(map/reduce)"
    }
]
```
Keep in mind that this would likely introduce additional overhead and may not provide meaningful results for small arrays.

Latest run results:

Run details: (Test run date: 11 months ago)

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/120.0.0.0 Safari/537.36 Edg/120.0.0.0

Browser/OS: Chrome 120 on Mac OS X 10.15.7

View result in a separate tab

Test name	Executions per second
filter(_ => _)	13122451.0 Ops/sec
filter(Boolean)	4093708.5 Ops/sec

Related benchmarks:

filter(_ => _) vs filter(Boolean) (version: 0)

Comparing performance of: filter(_ => _) vs filter(Boolean)

Created: 11 months ago by: Guest

Jump to the latest result

filter(_ => _)

filter(Boolean)

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 26 days ago):