Benchmark: Arrays into Object, reduce vs for #5

Script Preparation code:

var ppl = []
for(var i=0; i<20000; i++) {
	ppl.push({ id: i, name: i+"" }) 
}

Tests:

reduce
var byId = ppl.reduce((stored, current) => ({ ...stored, [current.id]: current }), {});
for
var byId = {} for(var i=0;i<ppl.length;i++) { byId[ppl[i].id] = ppl[i] }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
reduce
for

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 4 years ago)

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/86.0.4240.75 Safari/537.36

Browser/OS: Chrome 86 on Windows

View result in a separate tab

Test name	Executions per second
reduce	4.0 Ops/sec
for	112.7 Ops/sec

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

LLMs can make mistakes. Check important info.

Let's break down the provided JSON data to understand what is being tested.

**Benchmark Definition:**
The benchmark measures the performance of two approaches to create an object from an array:

1. **Array into Object, reduce**: This approach uses the `reduce` method to iterate over the array and create an object where each element in the array becomes a key-value pair.
2. **Array into Object, for**: This approach uses a traditional `for` loop to iterate over the array and create an object where each element in the array becomes a key-value pair.

**Options Compared:**

*   **Reduce Method:** The `reduce` method is a built-in JavaScript function that applies a specified function against an accumulator and each element of the array (from left to right) to reduce it to a single value.
*   **Traditional For Loop:** A traditional `for` loop uses an explicit counter variable to iterate over the elements of the array.

**Pros and Cons:**

*   **Reduce Method:**
    *   Pros:
        *   Concise and expressive code
        *   Can be more readable for complex transformations
        *   Often faster than traditional loops due to JavaScript's optimized implementation
    *   Cons:
        *   May be less intuitive for beginners or those unfamiliar with functional programming concepts
*   **Traditional For Loop:**
    *   Pros:
        *   Familiar and easy to understand for many developers
        *   Can be useful when working with complex logic or side effects that aren't well-suited for `reduce`
    *   Cons:
        *   Typically less concise than the `reduce` method
        *   May lead to more verbose code

**Library Usage:**
None of the provided benchmark definitions use any external libraries.

**Special JavaScript Features/Syntax:**
The provided benchmarks do not utilize any special JavaScript features or syntax, such as async/await, generators, or decorators. The focus is on comparing two common approaches to create an object from an array.

**Other Alternatives:**

*   For creating objects from arrays in general, other alternatives include:
    *   Using `Object.fromEntries` (a modern method introduced in ECMAScript 2019): `var byId = Object.fromEntries(ppl.map((ppl) => [ppl.id, ppl]));`
    *   Utilizing libraries like Lodash or Ramda for array utilities and functional programming

Keep in mind that the choice of approach often depends on the specific requirements and constraints of your project. The provided benchmarks aim to provide a neutral comparison between two common approaches, allowing developers to make informed decisions about their coding choices.

Related benchmarks:

Arrays into Object, reduce vs for #5 (version: 0)

https://www.youtube.com/watch?v=5nzBDkH9lWI

Comparing performance of: reduce vs for

Created: 4 years ago by: Guest

Jump to the latest result

reduce

for

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

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