Benchmark: flatMap vs reduce (with concat())

Script Preparation code:

var arr = Array(10_000).fill(0)

Tests:

Reduce
arr.reduce((acc, x) => acc.concat(x), [])
FlatMap
arr.flatMap(x => [x, x])

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Reduce
FlatMap

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 28 days ago):

LLMs can make mistakes. Check important info.

**What is being tested?**

MeasureThat.net is testing the performance difference between two JavaScript methods: `flatMap` and `reduce`, with an additional approach using `concat()`. The benchmark measures how many executions per second each method can perform on a large array of 10,000 zeros.

**Options compared**

The three approaches being compared are:

1. **FlatMap**: This method creates a new array by iterating over the original array and mapping each element to an array.
2. **Reduce**: This method applies a callback function to each element in the array, reducing it to a single value.
3. **FlatMap (with concat())**: This approach uses `reduce()` with an initial value of an empty array (`[]`) and then concatenates the results using the `concat()` method.

**Pros and Cons**

*   **flatMap**:
    *   Pros: Efficient, as it avoids creating a new array and instead directly returns the desired result.
    *   Cons: Can be less readable for those not familiar with its usage, especially when working with nested arrays.
*   **Reduce**:
    *   Pros: Highly flexible and can handle complex data structures, including reducing an array to a single value or multiple values.
    *   Cons: Inefficient in terms of performance compared to `flatMap`, as it creates new intermediate arrays.
*   **FlatMap (with concat())**:
    *   Pros: Can be more readable than using only `flatMap` for certain use cases, especially when working with nested arrays.
    *   Cons: Less efficient due to the creation of an additional array and concatenation.

**Library/Functionality**

There is no specific library being used in this benchmark. However, JavaScript has built-in functions like `Array.prototype.flatMap()` (introduced in ECMAScript 2019) that provide a similar functionality to `flatMap()`. The use of `concat()` is also a native JavaScript method for creating new arrays.

**Special JS feature/syntax**

This benchmark does not explicitly test any special JavaScript features or syntax. However, it assumes familiarity with the `flatMap()` and `reduce()` methods as well as basic understanding of array manipulation in JavaScript.

**Other alternatives**

If you're looking to implement this functionality without using `flatMap()`:

*   You can use loops or recursive functions to achieve similar results.
*   For `reduce()`, consider using libraries like Lodash that provide a more readable and efficient implementation.

In conclusion, the MeasureThat.net benchmark provides an excellent way to compare performance and readability between different JavaScript array methods. By understanding the pros and cons of each approach, developers can make informed decisions about which method best fits their needs.

Latest run results:

Run details: (Test run date: 2 years ago)

User agent: Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:97.0) Gecko/20100101 Firefox/97.0

Browser/OS: Firefox 97 on Ubuntu

View result in a separate tab

Test name	Executions per second
Reduce	1.2 Ops/sec
FlatMap	1326.0 Ops/sec

Related benchmarks:

flatMap vs reduce (with concat()) (version: 0)

Comparing performance of: Reduce vs FlatMap

Created: 2 years ago by: Guest

Jump to the latest result

Reduce

FlatMap

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 28 days ago):