Benchmark: forEach vs reduce

Script Preparation code:

var a = Array.from({length:100},()=>Math.random());
var b = [];

Tests:

forEach
a.forEach(e=>{if (e>0.5) b.push(e)});
reduce
b = a.reduce((a,c)=>c>0.5?a.concat(c):a,[])
reduce spread
b = a.reduce((a,c)=>c>0.5?[...a,c]:a,[])

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
forEach
reduce
reduce spread

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: one month ago)

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:150.0) Gecko/20100101 Firefox/150.0

Browser/OS: Firefox 150 on Mac OS X 10.15

View result in a separate tab

Test name	Executions per second
forEach	643286.6 Ops/sec
reduce	288903.3 Ops/sec
reduce spread	80391.5 Ops/sec

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

LLMs can make mistakes. Check important info.

Let's break down the provided benchmark and explain what's being tested.

**Benchmark Overview**

The benchmark compares three approaches for iterating over an array:

1. `forEach`
2. `reduce` (without using the spread operator)
3. `reduce` with the spread operator (`reduce spread`)

**Options Compared**

Here are the options being compared:

* `forEach`: This method calls a provided callback function once for each element in an array, without altering the original array.
* `reduce`: This method applies a reduction function to each element in an array and reduces it to a single value. In this case, we're using it as a simple iteration method, comparing its performance with `forEach`.
* `reduce spread`: This is similar to `reduce`, but uses the spread operator (`[...a, c]`) to create a new array for each iteration.

**Pros and Cons of Each Approach**

Here's a brief summary:

* `forEach`:
	+ Pros: Simple and widely supported, easy to understand.
	+ Cons: May be slower due to the creation of an intermediate array (in modern JavaScript engines).
* `reduce` (without spread):
	+ Pros: Can be more efficient than `forEach`, as it avoids creating an intermediate array.
	+ Cons: Less intuitive for simple iteration tasks, may require more memory allocation.
* `reduce spread`:
	+ Pros: Combines the benefits of both approaches, allowing for more flexibility in iteration and avoiding unnecessary array allocations.
	+ Cons: May be less efficient than using `forEach`, due to the additional overhead of creating a new array.

**Library Usage**

In this benchmark, none of the libraries are explicitly mentioned. However, it's likely that modern JavaScript engines (like V8) are implicitly used as the runtime environment for these tests.

**Special JS Features or Syntax**

There doesn't seem to be any special features or syntax being tested in this benchmark.

**Alternative Approaches**

Other alternatives for iterating over arrays include:

* Using `for` loops, which can be more efficient than array methods but may not provide the same level of abstraction.
* Utilizing libraries like `lodash.each` or `ramda.forEach`, which offer additional functionality and optimizations for iteration tasks.
* Leveraging modern JavaScript features like `async/await` or `Generator functions` for asynchronous iteration.

Keep in mind that these alternatives might not be directly comparable to the `forEach`, `reduce`, and `reduce spread` methods, as they often require different programming paradigms or context.

Related benchmarks:

forEach vs reduce (version: 0)

Comparing performance of: forEach vs reduce vs reduce spread

Created: 8 years ago by: Guest

Jump to the latest result

forEach

reduce

reduce spread

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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