Benchmark: Filter Boolean vs. Custom Function

Script Preparation code:

var arr = Array.from({length: 10000}, () => Math.random() > 0.5 ? null : "foo");

Tests:

filter(Boolean)
const numTruthy = arr.filter(Boolean).length; console.log(numTruthy);
filter function
const numTruthy = arr.filter(x => !!x).length; console.log(numTruthy);

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
filter(Boolean)
filter function

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_15_7) AppleWebKit/605.1.15 (KHTML, like Gecko) Version/18.3 Safari/605.1.15

Browser/OS: Safari 18 on Mac OS X 10.15.7

View result in a separate tab

Test name	Executions per second
filter(Boolean)	41445.6 Ops/sec
filter function	40824.4 Ops/sec

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

LLMs can make mistakes. Check important info.

Let's break down the provided JSON and explain what's being tested.

**Benchmark Definition:**

The benchmark is testing the performance of two approaches:

1. `filter(Boolean)`: This is an idiomatic way to filter out falsy values from an array in JavaScript. The `Boolean` function returns a value that is coerced to a boolean, which is then used as a predicate in the filtering process.
2. Filtering by a custom coercing function: In this approach, a custom function is used to coerce each element of the array to a boolean value before applying the filter.

**Options Compared:**

The benchmark is comparing the performance of two different approaches:

* `filter(Boolean)`: This approach uses the built-in `Boolean` function to coerce falsy values to `false`, which are then filtered out.
* Filtering by a custom coercing function: In this approach, a custom function is used to coerce each element of the array to a boolean value before applying the filter.

**Pros and Cons of Each Approach:**

1. `filter(Boolean)`:
	* Pros:
		+ Efficient, as it uses built-in functions that are optimized for performance.
		+ Easy to read and understand.
	* Cons:
		+ May not be suitable for all use cases, such as filtering arrays with non-boolean values.
2. Filtering by a custom coercing function:
	* Pros:
		+ More flexible than `filter(Boolean)`, as it allows for arbitrary coercion logic.
		+ Can be useful when dealing with complex data types or edge cases.
	* Cons:
		+ May have performance overhead due to the custom coercion logic.
		+ Requires more code and may be less readable.

**Library/Custom Function:**

In this benchmark, no external library is used. However, the `filter()` function itself is a built-in JavaScript method that returns an array of elements that pass the test implemented by the provided function.

**Special JS Feature/Syntax:**

There are no special JavaScript features or syntaxes mentioned in this benchmark. The focus is on comparing two different approaches to filtering arrays.

**Other Considerations:**

When writing benchmarks like this, it's essential to consider factors such as:

* Array size and distribution
* Data type and complexity
* Coercion logic (if applicable)
* Performance-critical code paths

In this case, the benchmark provides a small array of 10,000 elements with an equal split between truthy and falsy values. The custom coercing function is used to coerce each element to a boolean value before applying the filter.

**Alternatives:**

Other alternatives for filtering arrays in JavaScript might include:

* Using `Array.prototype.filter()` with a callback function
* Utilizing libraries like Lodash or Ramda for functional programming
* Implementing a custom filtering algorithm using loops and conditional statements

However, in this benchmark, the focus is on comparing two specific approaches: `filter(Boolean)` and filtering by a custom coercing function.

Related benchmarks:

Filter Boolean vs. Custom Function (version: 0)

Testing the performance of the idiomatic .filter(Boolean) vs. filtering by a custom coercing function.

Comparing performance of: filter(Boolean) vs filter function

Created: 2 years ago by: Guest

Jump to the latest result

filter(Boolean)

filter function

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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