Benchmark: forEach(item) vs forEach(item, index, array)

Script Preparation code:

var arr = ['1', '2', '3'];

Tests:

forEach(item) ...
var x; arr.forEach(function(item) { x = item * 10; });
forEach(function(item, index, array) ...
var x; arr.forEach(function(item, index, array) { // index && item not used x = item * 10; });

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
forEach(item) ...
forEach(function(item, index, array) ...

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 6 years ago)

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/69.0.3497.100 Safari/537.36

Browser/OS: Chrome 69 on Windows

View result in a separate tab

Test name	Executions per second
forEach(item) ...	8035538.5 Ops/sec
forEach(function(item, index, array) ...	7687259.0 Ops/sec

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

LLMs can make mistakes. Check important info.

I'd be happy to help you understand the JavaScript microbenchmarking test on MeasureThat.net.

**Benchmark Definition**

The benchmark tests two approaches of using the `forEach` method in JavaScript:

1. `arr.forEach(function(item) { ... })`
2. `arr.forEach(function(item, index, array) { ... })`

The goal is to measure the performance penalty when using the second approach with an additional `index` parameter.

**Options Compared**

The two options compared are:

* Using `forEach` with only one argument (i.e., `item`)
* Using `forEach` with three arguments (i.e., `item`, `index`, and `array`)

**Pros and Cons of Each Approach**

1. **Using `forEach` with one argument (`item`):**
	* Pros:
		+ Simplifies the code
		+ Reduces clutter by not having to declare a separate variable for the index
	* Cons:
		+ Can lead to slower performance due to the overhead of calculating the index internally
2. **Using `forEach` with three arguments (`item`, `index`, and `array`):**
	* Pros:
		+ Allows for more flexibility in handling the array elements
	* Cons:
		+ Requires declaring a separate variable for the index, which can increase code clutter

**Library Used**

The `forEach` method is a built-in JavaScript function. The purpose of `forEach` is to execute a callback function on each element of an array.

**Special JS Feature or Syntax**

There is no special feature or syntax mentioned in this benchmark that requires special consideration. However, it's worth noting that using `forEach` with three arguments can lead to additional overhead due to the need to pass the index and array references as separate arguments.

**Other Considerations**

When comparing the performance of these two approaches, other factors should be considered, such as:

* Array size: Smaller arrays may not show significant differences in performance.
* Browser and JavaScript engine variations: Different browsers and JavaScript engines may optimize `forEach` differently.
* Additional operations on the array elements: If additional operations are performed on each element (e.g., arithmetic operations), it can impact the performance difference between these two approaches.

**Alternative Benchmarks**

Other microbenchmarks that might be relevant to this one include:

* `for` loop vs. `forEach`
* Array iteration with `map`, `filter`, and `reduce` methods
* JavaScript array manipulation algorithms (e.g., sorting, searching)

Keep in mind that the specific benchmarking approach may depend on the use case and requirements of your project.

Related benchmarks:

forEach(item) vs forEach(item, index, array) (version: 0)

If we write the full prototype: arr.forEach(item, index, array) how much is the penalty?

Comparing performance of: forEach(item) ... vs forEach(function(item, index, array) ...

Created: 6 years ago by: Registered User

Jump to the latest result

forEach(item) ...

forEach(function(item, index, array) ...

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):