Benchmark: for vs foreach vs for..in vs for..of v2

Script Preparation code:

var array = new Array(100).fill(1);
let counter = 0;
var doStuff = (value) => counter += value;

Tests:

for
for (let i = 0; i < array.length; i++) { doStuff(array[i]); }
foreach
array.forEach((i) => { doStuff(array[i]); });
for in
for (const i in array) { doStuff(array[i]); }
for..of
for (const i of array) { doStuff(array[i]); }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
for
foreach
for in
for..of

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 2 years ago)

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/125.0.0.0 Safari/537.36 Edg/125.0.0.0

Browser/OS: Chrome 125 on Windows

View result in a separate tab

for..of

140K/s

for in

109K/s

foreach

96K/s

for

69K/s

View exact numbers

Test name	Executions per second
✓ for..of	140,495 Ops/sec
for in	109,243 Ops/sec
foreach	95,998 Ops/sec
for	69,157 Ops/sec

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

LLMs can make mistakes. Check important info.

I'd be happy to explain the benchmark and its different approaches.

**What is tested?**

The provided benchmark compares the performance of four different loop constructs in JavaScript:

1. Traditional `for` loop
2. `forEach` method
3. `for...in` loop
4. `for...of` loop (introduced in ECMAScript 2015)

Each test case measures the execution time for a specific loop construct, which is executed repeatedly to gather data.

**Loop constructs and their pros and cons:**

1. **Traditional `for` loop**:
	* Pros: simple, efficient, and widely supported.
	* Cons: can be verbose, especially when dealing with large loops or complex logic.
2. **`forEach` method**:
	* Pros: concise, easy to read, and well-suited for iterating over arrays or objects.
	* Cons: may incur a slight performance penalty due to the overhead of the `forEach` method.
3. **`for...in` loop**:
	* Pros: allows iteration over object properties, including inherited ones.
	* Cons: can be slow due to the overhead of property access and iteration.
4. **`for...of` loop** (introduced in ECMAScript 2015):
	* Pros: efficient, concise, and well-suited for iterating over arrays or iterables.
	* Cons: may not work as expected with older JavaScript engines or versions.

**Library usage**

None of the test cases use any external libraries. The `forEach` method is a built-in JavaScript function, while `for...in` loop and `for...of` loop are also part of the standard library.

**Special JS features or syntax**

The benchmark uses modern JavaScript features, including:

* Arrow functions (`=>`)
* Template literals (`\r\n`)
* ECMAScript 2015 syntax (`for...of`)

These features may not be supported in older JavaScript engines or versions.

**Other alternatives**

There are other loop constructs available in JavaScript, such as:

* `while` loop
* `do-while` loop
* `switch` statement (which can be used for iteration over cases)
* Generators and iterators (for handling asynchronous or infinite sequences)

However, these alternatives are not typically compared to traditional `for` loops, `forEach` method, or `for...in`/`for...of` loops in a benchmarking context.

In summary, the benchmark provides a fair comparison of four popular loop constructs in JavaScript, allowing users to evaluate their performance and choose the best option for specific use cases.

for vs foreach vs for..in vs for..of v2 (version: 0)

Compare loop performance

Comparing performance of: `for vs foreach vs for in vs for..of`

Created: 2 years ago by: Guest

Go to the latest result

for

foreach

for in

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):

for vs foreach vs for..in vs for..of v2 (version: 0)

Compare loop performance

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

Created: 2 years ago by: Guest

Go to the latest result

for

foreach

for in

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):

Related benchmarks

Comparing performance of: `for vs foreach vs for in vs for..of`