Benchmark: .flatMap() vs .map().flat()

Script Preparation code:

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

Tests:

map().flat()
arr.map(x => [x/100]).flat()
flatMap()
arr.flatMap(x => [x/100])

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
map().flat()
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 break down the benchmark and explain what's being tested.

**Benchmark Definition**

The benchmark is comparing two JavaScript methods: `flatMap()` and `.map().flat()`. Both methods are used to transform an array, but they have different behaviors when it comes to flattening nested arrays.

**Options Compared**

There are only two options being compared:

1. **`arr.flatMap(x => [x/100])`**: This method uses the `flatMap()` method to create a new array with the results of applying a provided function on every element in the calling array, and then flattening the resulting array.
2. **`arr.map(x => [x/100]).flat()`**: This method uses the `.map()` method to transform each element in the original array into an array, and then calls the `.flat()` method on the resulting nested arrays.

**Pros and Cons**

**`flatMap()`**:

* Pros:
	+ More concise and readable syntax
	+ Optimized for performance, as it avoids creating intermediate arrays
* Cons:
	+ Not supported in older browsers or versions of JavaScript
	+ Can be slower than `.map().flat()` due to the additional function call

**`.map().flat()`**:

* Pros:
	+ Widely supported across browsers and versions of JavaScript
	+ More predictable behavior, as it explicitly creates an intermediate array
* Cons:
	+ Less concise syntax
	+ May create intermediate arrays, which can be slower for large datasets

**Other Considerations**

In the benchmark code, a simple array `arr` is created with values from 0 to 100,000. This allows us to see how the different methods perform on a large dataset.

**Library and Purpose (if applicable)**

None of the test cases use any external libraries beyond the standard JavaScript functions (`map()`, `flatMap()`, `.flat()`).

No special JS features or syntax are used in this benchmark.

**Alternatives**

If you want to explore other options, here are some alternatives:

* **Other flattening methods**: You could add more options by comparing different flattening methods, such as using the spread operator (`[...arr]`) or recursion.
* **Different input datasets**: You could test the performance of the `flatMap()` and `.map().flat()` methods on smaller or larger datasets to see how they scale.
* **Other browsers or engines**: You could add more benchmark results for other browsers or JavaScript engines, such as Node.js or Safari, to see which one performs best.

Overall, this benchmark is a great starting point for exploring the performance differences between `flatMap()` and `.map().flat()`.

Related benchmarks:

.flatMap() vs .map().flat() (version: 0)

flatMap vs map flat

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

Created: 3 years ago by: Guest

Jump to the latest result

map().flat()

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):