Benchmark: if len-1 vs direct for-each

Script Preparation code:

var xs = [1];

function f(x) {
  return x;
}

Tests:

if then-1
if (xs.length === 1) { f(xs[0]); } else { xs.forEach(f); }
directly for-each
xs.forEach(f);
directly for-of
for (const x of xs) { f(x); }
directly for
for (let i = 0, n = xs.length; i < n; ++i) { f(xs[i]); }
for-each 2
xs.forEach(x => { f(x); });

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
if then-1
directly for-each
directly for-of
directly for
for-each 2

Fastest: N/A

Slowest: N/A

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

LLMs can make mistakes. Check important info.

I'll break down what's being tested in the provided JSON, explain the different approaches, their pros and cons, and discuss other considerations.

**Benchmark Definition**

The benchmark definition represents a JavaScript function that tests two different ways of checking if an array `xs` has only one element. The goal is to compare the performance of these different approaches.

**Script Preparation Code**

The script preparation code defines a variable `xs` as an array with one element, and a function `f(x)` that simply returns its input.

**Html Preparation Code**

There is no HTML preparation code provided, which means that only JavaScript execution time will be measured.

**Individual Test Cases**

The test cases represent different ways of checking if the array `xs` has only one element:

1. **if then-1**: Uses an if statement with a conditional check `if (xs.length === 1)`.
2. **directly for-each**: Uses the `forEach()` method to iterate over the array.
3. **directly for-of**: Uses the `for...of` loop syntax to iterate over the array.
4. **directly for**: Uses a traditional for loop with an index variable to access elements in the array.
5. **for-each 2**: Uses the `forEach()` method with an arrow function to iterate over the array.

**Library: none**

There are no libraries used in this benchmark definition.

**Special JavaScript Features or Syntax**

Only the `for...of` loop syntax is used, which is a relatively modern feature introduced in ECMAScript 2015 (ES6).

**Performance Comparison**

The results show that:

* **directly for-of**: The fastest approach, with an execution rate of approximately 19.8 executions per second.
* **for-each 2**: Very close to the performance of `directly for-of`, with an execution rate of approximately 17.3 executions per second.
* **directly for-each**: Slightly slower than the top two approaches, with an execution rate of approximately 17.2 executions per second.
* **if then-1** and **directly for**: The slowest approaches, with execution rates of approximately 13.0 and 12.9 executions per second, respectively.

The results suggest that using a `for...of` loop is the most efficient way to check if an array has only one element in JavaScript.

**Other Alternatives**

Other alternatives to these approaches could be:

* Using a simple conditional check like `if (xs.length > 1)` or `xs.length !== 1`.
* Using a more complex data structure, such as a `Map` or a `Set`, which may provide faster lookups.
* Optimizing the implementation of the `forEach()` method or other array methods.

However, these alternatives are not being tested in this benchmark definition.

Latest run results:

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

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/127.0.0.0 Safari/537.36

Browser/OS: Chrome 127 on Mac OS X 10.15.7

View result in a separate tab

Test name	Executions per second
if then-1	13096241.0 Ops/sec
directly for-each	16440073.0 Ops/sec
directly for-of	18798458.0 Ops/sec
directly for	12858363.0 Ops/sec
for-each 2	17293394.0 Ops/sec

Related benchmarks:

if len-1 vs direct for-each (version: 0)

if len-1 vs direct for-each

Comparing performance of: if then-1 vs directly for-each vs directly for-of vs directly for vs for-each 2

Created: 3 months ago by: Registered User

Jump to the latest result

if then-1

directly for-each

directly for-of

directly for

for-each 2

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

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