Benchmark: Tim's reduce vs flatMap

Script Preparation code:

var arr = new Array(10000).fill(0).map(() => [1,2]);

Tests:

reduce concating
console.log(arr.reduce((res,x) => [...res, x, x], []));
flatMap concating
console.log(arr.flatMap(x => [x, x]));

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
reduce concating
flatMap concating

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 26 days ago):

LLMs can make mistakes. Check important info.

**What is being tested?**

The provided JSON represents a benchmark test case on MeasureThat.net, where two different JavaScript functions are compared: `arr.reduce()` and `arr.flatMap()`. Both functions are designed to concatenate an array of arrays into a single array.

**Options compared**

The main difference between the two options is how they handle the inner arrays in the input data.

- `reduce()`: This function uses an accumulator (initially set to an empty array) to accumulate elements as it iterates through the array. It concatenates each element of the inner arrays to the accumulator, resulting in a new array.
- `flatMap()`: This function creates a new array with the results of applying a provided mapping function on every element in this array. In this case, it uses an arrow function to iterate through the inner arrays and concatenate each element.

**Pros and Cons**

- **Reduce()**:
  - Pros: More control over the concatenation process, can be used with other reduce operations.
  - Cons: May perform more iterations than necessary due to the use of an accumulator, potentially impacting performance.

- **flatMap()**: 
  - Pros: Typically faster, as it avoids unnecessary iterations and directly creates a new array with concatenated elements.
  - Cons: May have issues when dealing with deeply nested arrays or complex mapping functions.

**Library and purpose**

In this case, there is no explicitly mentioned library. However, the `Array.prototype.flatMap()` function has been part of the JavaScript standard since ECMAScript 2017 (ES7) as a replacement for `Array.prototype.map()`. It's generally considered a more efficient way to flatten arrays.

**Special JS feature or syntax**

This benchmark doesn't specifically highlight any special JavaScript features or syntax beyond what is standard in modern JavaScript (ECMAScript). However, it does demonstrate the use of arrow functions and array methods like `reduce()` and `flatMap()`, which are commonly used in modern JavaScript applications.

Latest run results:

Run details: (Test run date: 3 years ago)

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/93.0.4577.82 Safari/537.36

Browser/OS: Chrome 93 on Mac OS X 10.15.7

View result in a separate tab

Test name	Executions per second
reduce concating	7.5 Ops/sec
flatMap concating	222.5 Ops/sec

Related benchmarks:

Tim's reduce vs flatMap (version: 0)

Comparing performance of: reduce concating vs flatMap concating

Created: 3 years ago by: Guest

Jump to the latest result

reduce concating

flatMap concating

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 26 days ago):