Benchmark: For loop vs <Array>.forEach() vs for...of loop

Script Preparation code:

var array = Array(50000, (_, i) => i + 1);

Tests:

<Array>.forEach()
array.forEach(v => v);
For loop
for (let i = 0; i < array.length; i++) array[i];
For...of loop
for (let v of array) v;

Historical Performance Data aggregated from 9 community runs

Desktop Results:

Chrome 9 runs

<Array>.forEach()

87.6M/s

For...of loop

84.9M/s

For loop

55.4M/s

Fastest: <Array>.forEach() (1.6x faster)

View exact numbers

✓ <Array>.forEach(): 87,632,632 ops/sec
• For...of loop: 84,871,136 ops/sec
• For loop: 55,351,028 ops/sec

Results show median performance across all community submissions. Run this benchmark yourself to verify on your device.

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
<Array>.forEach()
For loop
For...of loop

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 20 days ago)

User agent: Mozilla/5.0 (iPhone; CPU iPhone OS 18_7 like Mac OS X) AppleWebKit/605.1.15 (KHTML, like Gecko) Version/27.0 Mobile/15E148 Safari/604.1

Browser/OS: Mobile Safari 27 on iOS 18.7

View result in a separate tab

For loop

587.0M/s

For...of loop

467.6M/s

<Array>.forEach()

86.8M/s

View exact numbers

Test name	Executions per second
✓ For loop	586,953,600 Ops/sec
For...of loop	467,563,936 Ops/sec
<Array>.forEach()	86,847,624 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 JSON benchmark definition and test cases.

**Benchmark Definition**

The benchmark is designed to compare the performance of three different approaches:

1. `array.forEach(v => v);`: This uses the `.forEach()` method on an array, which executes a callback function for each element in the array.
2. `for (let i = 0; i < array.length; i++) array[i];`: This uses a traditional `for` loop to iterate over the elements of the array and access them by index.
3. `for (let v of array) v;`: This uses the `for...of` loop, which iterates over an iterable object (like an array) and assigns each element to a variable.

**Options Compared**

The benchmark is comparing the performance of these three approaches:

* `.forEach()` method on arrays
* Traditional `for` loops
* `for...of` loops

**Pros and Cons**

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

1. `.forEach()` method:
	* Pros: concise, easy to read, and maintainable.
	* Cons: may not be as efficient as traditional loops for large arrays due to additional overhead.
2. Traditional `for` loop:
	* Pros: control over indexing, cache-friendliness, and can be optimized for specific use cases.
	* Cons: more verbose, harder to read and maintain, especially for complex logic.
3. `for...of` loop:
	* Pros: concise, easy to read, and maintainable (similar to `.forEach()`).
	* Cons: may not be as efficient as traditional loops due to the overhead of creating a new variable scope.

**Library Usage**

There is no explicit library usage in this benchmark definition. However, `Array` and its methods are part of the JavaScript standard library.

**Special JS Features or Syntax**

The only special feature used here is the `.forEach()` method on arrays, which is a built-in method provided by the JavaScript standard library (ECMAScript 2015). The other two approaches do not rely on any specialized features.

For loop vs <Array>.forEach() vs for...of loop (version: 0)

Comparing performance of: `<Array>.forEach() vs For loop vs For...of loop`

Created: 3 years ago by: Guest

Go to the latest result

<Array>.forEach()

For loop

For...of loop

Historical Performance Data aggregated from 9 community runs

Desktop Results:

Chrome 9 runs

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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

For loop vs <Array>.forEach() vs for...of loop (version: 0)

Comparing performance of: <Array>.forEach() vs For loop vs For...of loop

Created: 3 years ago by: Guest

Go to the latest result

<Array>.forEach()

For loop

For...of loop

Historical Performance Data aggregated from 9 community runs

Desktop Results:

Chrome 9 runs

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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

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Comparing performance of: `<Array>.forEach() vs For loop vs For...of loop`