Benchmark: For-loop - MeasureThat.net

Script Preparation code:

var arr = [1]

function test(x) {
 	return x * 3 + 2 
}

Tests:

for
for (var i = 0; i < arr.length; i++) { test(arr[i]) }
for-in
for (var i in arr) { test(arr[i]) }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
for
for-in

Fastest: N/A

Slowest: N/A

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

LLMs can make mistakes. Check important info.

Let's break down the provided JSON data and explain what's being tested on MeasureThat.net.

**Benchmark Definition**

The benchmark definition represents a simple JavaScript code snippet that uses a for loop to execute another function, `test`, on an array of numbers. The script preparation code is provided, which creates an array `arr` with one element and defines the `test` function that takes a single argument `x`. The `test` function returns the result of multiplying `x` by 3 and adding 2.

**Options Compared**

Two for loop variants are being compared:

1. **Traditional For Loop**: The first test case uses the traditional for loop syntax, which iterates over an array using an index variable (`i`) that increments from 0 to the length of the array.
```javascript
for (var i = 0; i < arr.length; i++) {
  test(arr[i]);
}
```
2. **For-in Loop**: The second test case uses the for-in loop syntax, which iterates over an object or array using a property name that is automatically generated by the engine.
```javascript
for (var i in arr) {
  test(arr[i]);
}
```
**Pros and Cons**

* **Traditional For Loop**:
	+ Pros: More explicit control over iteration variables and loop conditions. Can be more efficient for large arrays, as it avoids the overhead of property name lookup.
	+ Cons: May require manual indexing or array length checks, which can lead to bugs if not handled correctly.
* **For-in Loop**:
	+ Pros: Easier to write and read, as it abstracts away the iteration variable. Can be useful when iterating over objects with dynamic properties.
	+ Cons: Slower than traditional for loops due to property name lookup overhead. May require additional checks to avoid accessing undefined or non-existent properties.

**Other Considerations**

* **Array Length**: The benchmark definition uses an array of length 1, which is a small and fixed-size value. This might not accurately represent the performance characteristics of larger arrays.
* **Function Call Overhead**: The `test` function is called repeatedly inside the loop, but its execution time is not explicitly measured. This makes it difficult to isolate the performance impact of the for loop variant.

**Library**

None are mentioned in this specific benchmark definition.

**Special JS Feature or Syntax**

There are no special JavaScript features or syntax used in this benchmark definition. The focus is on comparing two basic for loop variants.

Now, let's consider some alternatives:

* **Other For Loop Variants**: MeasureThat.net might have explored other for loop variants, such as:
	+ `while` loops
	+ `forEach` methods (e.g., `arr.forEach(test)` )
	+ Iterators or generator functions
* **Array Iteration Methods**: The benchmark could have compared different array iteration methods, such as:
	+ `map()`
	+ `reduce()`
	+ `every()`
	+ `some()`

These alternatives might provide more comprehensive insights into JavaScript performance and optimization techniques.

Latest run results:

Run details: (Test run date: 7 years ago)

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_12_4) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/59.0.3071.115 Safari/537.36

Browser/OS: Chrome 59 on Mac OS X 10.12.4

View result in a separate tab

Test name	Executions per second
for	2488355.5 Ops/sec
for-in	1904812.5 Ops/sec

Related benchmarks:

For-loop (version: 0)

Comparing performance of: for vs for-in

Created: 7 years ago by: Guest

Jump to the latest result

for

for-in

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):