Benchmark: Do something 2 with for vs foreach vs some vs for..of

Script Preparation code:

var array = new Array(100);
var result = []

Tests:

for
for (var i = 0; i < array.length; i++) { result.push(array[i]); }
foreach
array.forEach(function(i) { result.push(array[i]); });
some
array.some(function(i) { result.push(array[i]); });
for..of
for (var i of array) { result.push(array[i]); }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
for
foreach
some
for..of

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 27 days ago):

LLMs can make mistakes. Check important info.

I'll break down the benchmark and explain what's being tested, compared, and the pros/cons of each approach.

**Benchmark Overview**

The benchmark compares the performance of four different loop constructs in JavaScript: traditional `for` loops, `forEach`, `some`, and `for...of`. The test measures how many times each loop executes per second.

**Script Preparation Code**

The script preparation code initializes an array with 100 elements and creates an empty result array. This sets the stage for the benchmark.

**Loop Constructs Being Compared**

1. **Traditional `for` loops**: `for (var i = 0; i < array.length; i++) { ... }`
	* Pros: Well-established, widely supported, and easy to understand.
	* Cons: Can be verbose and less efficient than other options.
2. **`forEach`**: `array.forEach(function(i) { result.push(array[i]); });`
	* Pros: Concise and easy to read. It's a built-in method in modern JavaScript, making it widely supported.
	* Cons: Can be slower than traditional loops for large datasets due to overhead from the iterator protocol.
3. **`some`**: `array.some(function(i) { result.push(array[i]); });`
	* Pros: Similar conciseness and ease of use as `forEach`. It's also a built-in method, making it widely supported.
	* Cons: Less intuitive for developers who don't understand the difference between `forEach` and `some`.
4. **`for...of`**: `for (var i of array) { result.push(array[i]); }`
	* Pros: Concise and easy to read, especially for iterating over arrays or iterable objects.
	* Cons: Less widely supported than traditional loops, as it's a relatively new feature introduced in ECMAScript 2015.

**Library Used**

None. The benchmark only uses built-in JavaScript methods and doesn't rely on any external libraries.

**Special JS Feature/Syntax**

None mentioned in this explanation, but `for...of` is a relatively new feature introduced in ECMAScript 2015, which might require a specific version of JavaScript engine or runtime to support.

**Other Alternatives**

In addition to the loop constructs being compared, other alternatives could include:

* Using array destructuring: `const [i] = array; result.push(i);`
* Using `map()`: `array.map(function(i) { return result.push(array[i]); });`
* Using a `while` loop: `var i = 0; while (i < array.length) { result.push(array[i]); ++i; }`

These alternatives might be worth considering in specific scenarios, but they're not part of the original benchmark.

**Benchmark Result Interpretation**

The benchmark results show the number of executions per second for each loop construct. A higher value indicates faster performance. The "some" loop performs best, followed closely by the traditional `for` loops. The `forEach` and `for...of` loops perform slightly slower, likely due to the overhead from their respective iterator protocols.

Keep in mind that these results are specific to this benchmark and might not generalize well to other scenarios or use cases.

Latest run results:

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

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:88.0) Gecko/20100101 Firefox/88.0

Browser/OS: Firefox 88 on Mac OS X 10.15

View result in a separate tab

Test name	Executions per second
for	275022.2 Ops/sec
foreach	3373631.8 Ops/sec
some	8599792.0 Ops/sec
for..of	139848.4 Ops/sec

Related benchmarks:

Do something 2 with for vs foreach vs some vs for..of (version: 0)

Compare loop performance

Comparing performance of: for vs foreach vs some vs for..of

Created: 3 years ago by: Registered User

Jump to the latest result

for

foreach

some

for..of

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 27 days ago):