Benchmark: for vs foreach vs some vs for..of big (over a million runs)

Script Preparation code:

var array = new Array(1714176);

Tests:

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

Latest run results:

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

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/128.0.0.0 Safari/537.36 Edg/128.0.0.0

Browser/OS: Chrome 128 on Windows

View result in a separate tab

Test name	Executions per second
for	4.1 Ops/sec
foreach	224.6 Ops/sec
some	221.2 Ops/sec
for..of	5.4 Ops/sec

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

LLMs can make mistakes. Check important info.

The provided JSON represents a JavaScript microbenchmarking test on the MeasureThat.net website. The benchmark compares the performance of four different loop structures: traditional `for`, `forEach`, `some`, and the newer `for..of` syntax.

Let's break down each option:

1. **Traditional `for`**: This is the most basic type of loop, where the index variable `i` is explicitly declared and incremented. The pros of this approach are:
	* High performance, as it allows for direct indexing into the array.
	* Easy to implement and understand.
The cons are:
	* Index-related errors can be tricky to avoid.
2. **`forEach`**: This loop structure iterates over an array using a callback function that is applied to each element. The pros of this approach are:
	* Less prone to index-related errors, as the callback function handles indexing internally.
	* Can be more readable and maintainable for some use cases.
The cons are:
	* May incur additional overhead due to the callback function's execution.
3. **`some`**: This loop structure returns `true` as soon as it finds an element that passes a test, short-circuiting further iterations. The pros of this approach are:
	* Can be more efficient for large arrays, as it stops iterating early.
The cons are:
	* Less intuitive and less readable than other options.
4. **`for..of`**: This newer syntax uses the `for...of` loop to iterate over an array, which is similar to `forEach`. However, it provides a more concise and expressive way of writing loops. The pros of this approach are:
	* More concise and readable than traditional `for`.
The cons are:
	* May incur additional overhead due to the new syntax's parsing.

Now, let's analyze the latest benchmark results:

The results show that:

* **`forEach`** performs best with an average execution rate of 224.59 executions per second.
* **`some`** is close behind, with an average execution rate of 221.20 executions per second.
* **`for..of`** and **traditional `for`** perform significantly slower, with average execution rates of 5.38 and 4.15 executions per second, respectively.

The reasons for these differences are:

* **`forEach`** likely incurs additional overhead due to the callback function's execution.
* **`some`** stops iterating early, which is beneficial for large arrays.
* **`for..of`** and traditional `for` may have slower performance due to their syntax and parsing overhead.

Other alternatives that are not included in this benchmark but worth mentioning include:

* **Arrow functions**: These can be used with `forEach` or `some` loops, providing a concise way of writing callbacks.
* **Generator functions**: These can be used with `for...of` loops, allowing for more expressive and efficient iteration over arrays.

Overall, the results suggest that **`forEach`** is the most performant option, followed closely by **`some`**. The newer **`for..of`** syntax and traditional `for` are slower due to their syntax and parsing overhead.

Related benchmarks:

for vs foreach vs some vs for..of big (over a million runs) (version: 0)

Compare loop performance

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

Created: one year ago by: Guest

Jump to the latest result

for

foreach

some

for..of

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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