Benchmark: .forEach vs for const of

Script Preparation code:

var a = [...Array(10000).keys()];
var sum = 0;

Tests:

.forEach
a.forEach(i => sum += i)
for const of
for (const i of a) { sum += i; }

Historical Performance Data aggregated from 7 community runs

Desktop Results:

Chrome 7 runs

.forEach

1K/s

for const of

1K/s

View exact numbers

✓ .forEach: 1,357 ops/sec
• for const of: 1,345 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
.forEach
for const of

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: one year ago)

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/136.0.0.0 Safari/537.36

Browser/OS: Chrome 136 on Mac OS X 10.15.7

View result in a separate tab

.forEach

2K/s

for const of

2K/s

View exact numbers

Test name	Executions per second
✓ .forEach	2,061 Ops/sec
for const of	2,045 Ops/sec

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

LLMs can make mistakes. Check important info.

Let's dive into the provided benchmark and explain what's being tested.

**Benchmark Definition**

The provided JSON defines two benchmark tests: `.forEach` and `for const of`. These are both used to iterate over an array, but they use different approaches to achieve this.

**Options Compared**

The two options being compared are:

1. `.forEach`: This method iterates over the elements of an array using a callback function. The callback function is called for each element in the array, and it receives the current element as an argument.
2. `for const of`: This is a newer syntax introduced in ECMAScript 2017 (ES7). It uses a `for...of` loop to iterate over an iterable object (such as an array) without exposing its internal implementation details.

**Pros and Cons**

Both approaches have their advantages and disadvantages:

* `.forEach`:
	+ Pros: Widely supported, easy to use, and compatible with older browsers.
	+ Cons: Can be less efficient than `for const of`, as it creates a new scope for each iteration, which can lead to increased memory usage.
* `for const of`:
	+ Pros: More efficient, as it avoids the overhead of creating a new scope for each iteration. It also provides better performance, as it uses a more optimized internal loop implementation.
	+ Cons: Requires modern JavaScript engines (like Chrome 119) to execute, and might not be compatible with older browsers or environments.

**Library Usage**

There is no library used in this benchmark.

**Special JS Features/Syntax**

The `for const of` syntax uses the `for...of` loop, which was introduced in ECMAScript 2017 (ES7). This syntax allows you to iterate over an array without exposing its internal implementation details. It's a more modern and efficient way of iterating over arrays compared to the traditional `.forEach` method.

**Other Alternatives**

If you're interested in exploring other alternatives for iterating over arrays, here are a few:

1. `for...in`: This loop iterates over an object's properties using their keys.
2. `map()`, `filter()`, and `reduce()`: These methods are used to transform or filter arrays without iterating over them directly.

In conclusion, the provided benchmark compares two approaches for iterating over arrays: `.forEach` and `for const of`. The `for const of` syntax is a more modern and efficient way of iterating over arrays, but it requires modern JavaScript engines to execute.

.forEach vs for const of (version: 0)

Comparing performance of: `.forEach vs for const of`

Created: 4 years ago by: Registered User

Go to the latest result

.forEach

for const of

Historical Performance Data aggregated from 7 community runs

Desktop Results:

Chrome 7 runs

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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

.forEach vs for const of (version: 0)

Comparing performance of: .forEach vs for const of

Created: 4 years ago by: Registered User

Go to the latest result

.forEach

for const of

Historical Performance Data aggregated from 7 community runs

Desktop Results:

Chrome 7 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: `.forEach vs for const of`