Benchmark: foreach vs map vs for in v2

Script Preparation code:

var array = new Array(100);

Tests:

foreach
array.forEach(function(item, index) { return item; });
arr map
array.map(function(item) { return item; });
for of
for (const item of array) { item; }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
foreach
arr map
for of

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 26 days 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 measures the performance of three different approaches to iterate over an array: `forEach`, `map`, and `for-of`. The goal is to determine which approach is the fastest for a given use case.

**Library Usage**

In the benchmark, the `array` object is used, which is a built-in JavaScript object. No external libraries are required or used in this benchmark.

**Special JS Feature/Syntax**

The benchmark uses the new `for...of` loop syntax introduced in ECMAScript 2015 (ES6). This syntax allows you to iterate over an array without the need for explicit indexing or manual iteration.

**Options Compared**

Here's a summary of what's being compared:

* **`forEach`**: Uses the traditional `forEach()` method, which takes two arguments: a callback function and an optional context object.
* **`map`**: Uses the `map()` method, which also takes a callback function as its first argument. However, it returns a new array with the results of applying the callback to each element in the original array.
* **`for-of`**: Uses the new `for...of` loop syntax, which allows you to iterate over an array without using indexing or manual iteration.

**Pros and Cons**

Here's a brief pros and cons summary for each approach:

* **`forEach`**:
	+ Pros: Wide support across browsers, easy to use.
	+ Cons: Can be slower than other methods due to the need to access the `item` value twice (once in the callback and once as the loop variable).
* **`map`**:
	+ Pros: Returns a new array with transformed values, can be useful for data processing pipelines.
	+ Cons: Can be slower than `forEach` because it creates a new array and copies elements over.
* **`for-of`**:
	+ Pros: More concise and expressive syntax, often faster due to reduced overhead from indexing and manual iteration.
	+ Cons: May not be as widely supported across browsers or older JavaScript versions.

**Benchmark Results**

The latest benchmark results show that:

* `foreach`: 4316745 executions per second
* `for of`: 3600731 executions per second
* `arr map`: 2751032.25 executions per second

Based on these results, it appears that the `for-of` approach is currently the fastest for this benchmark.

**Alternatives**

If you need to compare other iteration methods or want more control over your iterations, some alternatives include:

* **Manual iteration**: Using indexing (e.g., `array[index]`) to access elements and update indices.
* **While loops**: Using a while loop with manual indexing to iterate over an array.
* **Other libraries**: Depending on the specific use case, you may need to use external libraries like Lodash or Ramda for more advanced iteration methods.

Keep in mind that these alternatives might not be as performant or widely supported as the `forEach`, `map`, and `for-of` methods.

Latest run results:

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

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_1) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/78.0.3904.108 Safari/537.36

Browser/OS: Chrome 78 on Mac OS X 10.15.1

View result in a separate tab

Test name	Executions per second
foreach	4316745.0 Ops/sec
arr map	2751032.2 Ops/sec
for of	3600731.0 Ops/sec

Related benchmarks:

foreach vs map vs for in v2 (version: 0)

Comparing performance of: foreach vs arr map vs for of

Created: 4 years ago by: Guest

Jump to the latest result

foreach

arr map

for of

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):