Benchmark: for of vs foreach vs for 123

Script Preparation code:

var arr = new Array(10000).map((v, i) => i)

Tests:

for of
let result = 0; for (const item of arr) { result += item; }
forEach
let result = 0; arr.forEach(i => result += i)
for
let result = 0; for (let i = 0; i < arr.length; i++) { result += arr[i]; }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
for of
forEach
for

Fastest: N/A

Slowest: N/A

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.

**Benchmark Overview**

The benchmark compares three different approaches to iterating over an array in JavaScript: `for of`, `forEach`, and traditional `for` loops. The goal is to determine which approach is the fastest.

**Script Preparation Code**

The script preparation code creates a new array with 10,000 elements, where each element is its index (`i`) using the arrow function syntax:
```javascript
var arr = new Array(10000).map((v, i) => i);
```
This ensures that the array has a consistent structure and size across all test cases.

**Html Preparation Code**

There is no HTML preparation code provided, which means the benchmark only runs in Node.js or other JavaScript environments without a DOM.

**Test Cases**

The three test cases are:

1. **`for of`**: Uses the `for...of` loop to iterate over the array.
2. **`forEach`**: Uses the `forEach()` method to iterate over the array.
3. **`for`**: Uses a traditional `for` loop with an index variable (`i`) to iterate over the array.

**Library Usage**

There is no library usage mentioned in the benchmark definition or test cases. However, some browsers (like Chrome) may use optimized implementations of these constructs that are not explicitly exposed as libraries.

**Special JavaScript Features/Syntax**

* The `for...of` loop is a relatively recent feature introduced in ECMAScript 2015 (ES6). It's designed to iterate over iterable objects, such as arrays, and provides a more concise syntax.
* The `forEach()` method is also a built-in method for iterating over arrays.

**Pros and Cons of Each Approach**

Here are some general pros and cons of each approach:

1. **`for...of`**:
	* Pros: More concise syntax, easier to read and write, works with any iterable object.
	* Cons: May have slower performance due to the overhead of creating an iterator.
2. **`forEach()`**:
	* Pros: Concise syntax, easy to use, works with arrays and other iterables.
	* Cons: May not be as readable or maintainable as `for...of` or traditional `for` loops.
3. **Traditional `for` Loop**:
	* Pros: Well-established syntax, easy to understand, allows for fine-grained control over iteration.
	* Cons: More verbose, may have slower performance due to the need to manually increment and check indices.

**Other Alternatives**

If you're interested in exploring alternative approaches, here are a few options:

1. **`map()`**: Instead of using `for...of`, `forEach()`, or traditional `for` loops, you can use the `map()` method to create a new array with transformed values.
2. **Generators**: Generators are a type of iterable that allow you to yield values one at a time, which can be useful for creating iterative algorithms.
3. **Reduce()`: The `reduce()` method is another built-in method for iterating over arrays and accumulating values.

These alternatives may offer different trade-offs in terms of performance, readability, or maintainability, so it's worth exploring each option to see which best fits your use case.

Latest run results:

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

User agent: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/87.0.4280.88 Safari/537.36

Browser/OS: Chrome 87 on Linux

View result in a separate tab

Test name	Executions per second
for of	37145.3 Ops/sec
forEach	54878.9 Ops/sec
for	638.1 Ops/sec

Related benchmarks:

for of vs foreach vs for 123 (version: 0)

Comparing performance of: for of vs forEach vs for

Created: 4 years ago by: Guest

Jump to the latest result

for of

forEach

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):