Benchmark: forEach vs Flatmap

Script Preparation code:

var arr = ([{
    name: 1,
    list: [2]
}, {
    name: 3,
    list: [4]
}])

Tests:

testcase forEach
var flatten = []; arr.forEach(el => {flatten.push(el)});
testcase FlatMap
var flatten = arr.flatMap((el) => el.list)

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
testcase forEach
testcase FlatMap

Fastest: N/A

Slowest: N/A

Latest run results:

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

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/112.0.0.0 Safari/537.36

Browser/OS: Chrome 112 on Windows

View result in a separate tab

Test name	Executions per second
testcase forEach	4431935.5 Ops/sec
testcase FlatMap	819572.2 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 benchmark and explain what's being tested, compared, and some pros and cons of each approach.

**What's being tested?**

The benchmark compares two approaches to process an array: `forEach` and `flatMap`. Specifically, it measures the performance difference between these two methods on a sample array of objects with nested arrays.

**Options compared:**

1. **forEach**: Iterates over the elements of an array using a callback function.
2. **flatMap**: A method introduced in ECMAScript 2019 (ES2019) that flattens an array by mapping each element to an array and then flattening the result.

**Pros and cons of each approach:**

1. **forEach**:
	* Pros:
		+ Widely supported across browsers and Node.js versions.
		+ Easy to read and understand, especially for developers familiar with callback functions.
	* Cons:
		+ Can lead to slower performance due to the overhead of creating an array and calling `push()` on it in each iteration.
		+ May cause memory issues if not handled properly (e.g., pushing large objects into arrays).
2. **flatMap**:
	* Pros:
		+ Designed specifically for flattening arrays, making it more efficient than `forEach`.
		+ Reduces the number of array allocations and copies, resulting in better performance.
	* Cons:
		+ Introduced in ES2019, so some older browsers or environments might not support it.
		+ May require additional imports or polyfills for compatibility.

**Library used:**

In this benchmark, no libraries are explicitly mentioned. However, the use of `flatMap` implies that the browser or environment supports the ECMAScript 2019 standard.

**Special JS feature:**

The benchmark uses ES2019's `flatMap` method, which is a relatively new addition to the JavaScript language. This feature allows for concise and efficient array processing.

**Other alternatives:**

For those who prefer not to use `flatMap`, other alternatives can be used:

1. **Array.prototype.reduce()**: Can be used in combination with `Map()` to achieve similar results.
2. **Array.prototype.forEach() + Array.prototype.map()**: This approach is less elegant but still works by using `forEach` to iterate and then mapping each result.

In summary, the benchmark compares the performance of `forEach` versus `flatMap`, highlighting the benefits of the newer method for array processing. While `forEach` has been widely adopted, `flatMap` provides a more efficient solution in recent JavaScript versions.

Related benchmarks:

forEach vs Flatmap (version: 0)

Comparing performance of: testcase forEach vs testcase FlatMap

Created: one year ago by: Guest

Jump to the latest result

testcase forEach

testcase FlatMap

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):