Benchmark: Benchmark: flatMap vs reduce vs while

Script Preparation code:

var n = 1000

Tests:

flatMap
[...Array(n)].flatMap((x,i) => [++i,i++])
reduce
[...Array(n).keys()].reduce((acc, cur) => [...acc, ++cur, cur++], [])
while
let res = [], i=0; while(n>i++) res.push(i, i);

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
flatMap
reduce
while

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 27 days ago):

LLMs can make mistakes. Check important info.

Let's break down the provided benchmark and its test cases.

**What is being tested?**

MeasureThat.net is testing three different JavaScript methods for flattening an array: `flatMap`, `reduce`, and a manual loop using `while`. The goal is to determine which method performs best in terms of execution speed.

**Options compared:**

*   **`flatMap`**: A modern JavaScript method that returns a new array with the results of applying a provided function on every element of an array. In this case, it's used to flatten an array by mapping over each element and returning an array containing two values.
*   **`reduce`**: Another modern JavaScript method that applies a callback function to each element in an array (in this case, an array of keys), reducing the array into a single output value. However, in this test case, it's used to flatten the array by pushing elements onto another array inside the callback.
*   **Manual loop using `while`**: A traditional approach that uses a while loop to iterate over each element in the array and push its contents onto another array.

**Pros and cons of different approaches:**

*   **`flatMap`**:
    *   Pros: Modern, concise syntax. It's often faster due to its native implementation.
    *   Cons: May not be supported by older browsers or JavaScript versions. Some developers might find it less intuitive due to the use of arrow functions and the `map()` method.
*   **`reduce`**:
    *   Pros: Also modern, concise syntax. It's often faster than manual loops for array operations. However, it requires a callback function that can handle accumulating values.
    *   Cons: May not be supported by older browsers or JavaScript versions like `flatMap`. Some developers might find it less intuitive due to the use of callback functions.
*   **Manual loop using `while`**:
    *   Pros: Typically the most compatible approach with older browsers and versions. However, can result in slower execution compared to modern methods like `flatMap` or `reduce`.
    *   Cons: Often requires more code and is less concise.

**Library usage**

In this benchmark, there are no libraries being used beyond the standard JavaScript features.

**Special JS feature/syntax**

*   **Arrow functions**: Used in both `flatMap` and `reduce` test cases. Arrow functions provide a shorter syntax for defining small anonymous functions.
*   **Spread operator (`...`)**: Used to expand arrays or objects into individual elements within methods like `map()` and `push()`.
*   **Template literals (``) with backticks**: Used in the script preparation code to concatenate strings and variables. This feature is a part of ECMAScript 2015+.

**Other alternatives**

For testing performance, MeasureThat.net might compare:

*   Array methods like `forEach`, `map`, `filter`, or `sort`.
*   Object methods such as `Object.keys()`, `Object.values()`, or `Object.entries()`.
*   DOM-based operations for web applications.
*   Other languages or libraries, depending on the specific use case.

Please note that performance results may vary based on specific hardware configurations and JavaScript environments.

Latest run results:

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

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/103.0.5060.114 Safari/537.36

Browser/OS: Chrome 103 on Mac OS X 10.15.7

View result in a separate tab

Test name	Executions per second
flatMap	5947.1 Ops/sec
reduce	1318.5 Ops/sec
while	25410.3 Ops/sec

Related benchmarks:

Benchmark: flatMap vs reduce vs while (version: 0)

Comparing performance of: flatMap vs reduce vs while

Created: 3 years ago by: Guest

Jump to the latest result

flatMap

reduce

while

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 27 days ago):