Benchmark: flatMap() vs filter() oof

Script Preparation code:

var arr = [];
var i = 0;

while (i <= 1E5) arr[i] = i++;

Tests:

filter().map()
arr.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:

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

LLMs can make mistakes. Check important info.

Let's dive into the world of MeasureThat.net and explore what's being tested in this benchmark.

**What is being tested?**

The provided JSON represents two individual test cases, each testing different approaches to filtering an array: `filter()` vs `flatMap()`. The scripts preparation code generates a large array of numbers, which serves as the input for these functions.

**Options compared**

Two options are being compared:

1. **`filter()`**: This method creates a new array with all elements that pass the test implemented by the provided function.
2. **`flatMap()`**: This method creates a new array with the results of applying the provided function to each element in the calling array.

**Pros and Cons**

* **`filter()`**:
	+ Pros: Simple, efficient, and widely supported.
	+ Cons: May not be as performant as `flatMap()` for certain use cases, as it creates a new array with all filtered elements.
* **`flatMap()`**:
	+ Pros: More efficient than `filter()` when dealing with arrays of arrays or other complex data structures, as it avoids creating intermediate arrays.
	+ Cons: May be less intuitive to understand and implement, especially for those not familiar with functional programming concepts.

In general, `filter()` is suitable for simple filtering tasks, while `flatMap()` is better suited for more complex scenarios where you need to process each element in the array and return a new array of results.

**Library**

There is no library explicitly mentioned in the JSON. However, both `filter()` and `flatMap()` are built-in methods in JavaScript's Array prototype, making them available for use without any external dependencies.

**Special JS feature/syntax**

The test case uses the `flatMap()` method, which was introduced in ECMAScript 2019 (ES2020). It's a relatively new feature that allows for more efficient array operations. However, it's worth noting that older JavaScript engines might not support this method or may have varying levels of performance optimization.

**Other alternatives**

For those who prefer to use loops instead of built-in methods:

* **`filter()`**: You can achieve the same result using a traditional `for` loop: `arr = arr.filter(x => x % 3);`
* **`flatMap()`**: Similarly, you can use a `for` loop with conditional statements: `arr = arr.flatMap(x => x % 3 ? [] : [x/100]);`

Alternatively, if you prefer to use libraries like Lodash or Ramda for functional programming, you can also implement these methods using those frameworks.

Keep in mind that the choice of approach ultimately depends on your specific use case, personal preference, and performance requirements.

Related benchmarks:

flatMap() vs filter() oof (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):