Benchmark: array from map vs foreach

HTML Preparation code:

<div class="name"><div class="name"><div class="name">

Tests:

Array.from + map
Array.from(document.querySelectorAll('.name')).map(element => { console.log(element); });
foreach
document.querySelectorAll('.name').forEach(element => { console.log(element); });

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Array.from + map
foreach

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 3 years ago)

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:89.0) Gecko/20100101 Firefox/89.0

Browser/OS: Firefox 89 on Windows

View result in a separate tab

Test name	Executions per second
Array.from + map	7468.1 Ops/sec
foreach	7617.7 Ops/sec

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

LLMs can make mistakes. Check important info.

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

**Benchmark Overview**

The benchmark compares the performance of two approaches: using `forEach` loop to iterate over an array, versus using `Array.from()` method with a callback function to create an array from another array. The goal is to measure which approach is faster.

**Library Used**

In this benchmark, a JavaScript library called `document.querySelector()` and its alias `document.querySelectorAll()` are used to retrieve elements from the DOM. These methods are part of the W3C DOM API and provide a way to query an HTML document to find specific elements. The purpose of using these libraries is to create a test case that simulates real-world scenarios where JavaScript code needs to iterate over DOM elements.

**Special JS Feature/Syntax**

The benchmark uses the `arrow function` syntax, which was introduced in ECMAScript 2015 (ES6). Arrow functions are a concise way to define small functions. They are defined using the `=>` operator and have several benefits, such as avoiding the need to declare `this` context explicitly.

**Test Cases**

There are two test cases:

1. **"Array.from + map"`**: This test case creates an array from the DOM elements retrieved using `document.querySelectorAll('.name')`, and then maps over the array, logging each element to the console.
2. **"foreach"`**: This test case uses a traditional `forEach` loop to iterate over the same DOM elements retrieved using `document.querySelectorAll('.name')`, also logging each element to the console.

**Options Compared**

The benchmark compares two options:

* Using `Array.from()` method with a callback function (Test Case 1: "Array.from + map")
* Using a traditional `forEach` loop (Test Case 2: "foreach")

**Pros and Cons of Each Approach**

* **Using `Array.from()`**: Pros:
	+ More concise syntax
	+ Avoids the need to declare `this` context explicitly
	+ Can be faster in some cases, as it avoids the overhead of a traditional loop
Cons:
	+ May not work correctly for older browsers or environments that don't support the `Array.prototype.from()` method
* **Using `forEach`**: Pros:
	+ Works on older browsers and environments
	+ Easy to understand and implement
Cons:
	+ Less concise syntax
	+ Can be slower due to the overhead of a traditional loop

**Other Alternatives**

There are other alternatives to using `Array.from()` and `forEach`, such as:

* Using `slice()` method to create a new array (instead of `Array.from()`)
* Using a traditional `for` loop or a `while` loop
* Using libraries like Lodash or Ramda for functional programming approaches

Keep in mind that the choice of approach depends on the specific use case, performance requirements, and compatibility with different browsers and environments.

Related benchmarks:

array from map vs foreach (version: 0)

Comparing performance of: Array.from + map vs foreach

Created: 3 years ago by: Guest

Jump to the latest result

Array.from + map

foreach

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

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