Benchmark: flatMap() vs map().filter() small

Script Preparation code:

var arr = [];
var i = 0;

while (i <= 20) arr[i] = i++;

Tests:

filter().map()
arr.map(x => x/100).filter(x => x % 3)
flatMap()
arr.flatMap(x => x % 3 ? x/100 : [])

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
filter().map()
flatMap()

Fastest: N/A

Slowest: N/A

Latest run results:

No previous run results

This benchmark does not have any results yet. Be the first one to run it!

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

LLMs can make mistakes. Check important info.

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

**Benchmark Overview**

The benchmark compares two approaches to flatten an array in JavaScript: `flatMap()` versus `map().filter()`. The goal is to determine which approach is faster and more efficient for this specific use case.

**Options Compared**

Two options are compared:

1. **`map().filter()`**: This approach uses the `map()` method to create a new array with the transformed values, and then applies the `filter()` method to remove elements that don't meet the condition.
2. **`flatMap()`**: This is a newer method introduced in ECMAScript 2019, which combines the functionality of both `map()` and `reduce()`. It flattens an array by mapping each element to an array and then flattening the resulting arrays.

**Pros and Cons**

* **`map().filter()`**:
	+ Pros: Well-established and widely supported method. Easy to understand and implement.
	+ Cons: Can be slower due to the overhead of creating a new array with `map()`, followed by filtering the entire array with `filter()`.
* **`flatMap()`**:
	+ Pros: More efficient than the traditional approach, as it avoids creating unnecessary intermediate arrays. It's also more concise and expressive.
	+ Cons: Less well-known and supported in older browsers or environments that don't have native support for `flatMap()`.

**Library Usage**

There is no explicit library mentioned in the benchmark definition or test cases. However, the `map()`, `filter()`, and `flatMap()` methods are part of the ECMAScript standard and are available in most modern JavaScript engines.

**Special JS Feature/Syntax**

The benchmark uses a relatively new feature: **`flatMap()`**. Introduced in ECMAScript 2019, this method is designed to simplify array flattening operations. It's supported by most modern browsers and JavaScript engines.

**Other Alternatives**

If `flatMap()` is not supported or desired, other approaches can be used:

1. Using `map()` with a callback function that returns an empty array for elements that don't meet the condition.
2. Using `reduce()` to flatten the array, as mentioned in the benchmark's alternative approach (`arr.flatMap(x => x % 3 ? x/100 : [])`).

These alternatives may not be as efficient or concise as using `flatMap()`, but they can provide a viable fallback when native support is lacking.

In summary, the benchmark compares two approaches to flatten an array: the traditional `map().filter()` method and the newer, more efficient `flatMap()` method. The test results show that `flatMap()` outperforms the traditional approach in this specific use case.

Related benchmarks:

flatMap() vs map().filter() small (version: 0)

flatMap vs filter map

Comparing performance of: filter().map() vs flatMap()

Created: 3 years ago by: Guest

Jump to the latest result

filter().map()

flatMap()

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):