Benchmark: Loop Comprasion - MeasureThat.net

Script Preparation code:

var MyArray = Array(1000).fill({
        description:
          'Creates a deep copy of source, which should be an object or an array.',
        myNumber: 123456789,
        myBoolean: true,
        jayson: {
          stringify:
            'JSON.stringify() method converts a JavaScript value to a JSON string....',
          parse: 'JSON.parse() method parses a JSON string...',
        },
      });

Tests:

chain forEach
MyArray.forEach((item)=>{ console.log(item.myNumber); });
for-in
for(const item in MyArray) { console.log(item.myNumber); }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
chain forEach
for-in

Fastest: N/A

Slowest: N/A

Latest run results:

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

User agent: Mozilla/5.0 (Linux; Android 10; K) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/122.0.0.0 Mobile Safari/537.36

Browser/OS: Chrome Mobile 122 on Android

View result in a separate tab

chain forEach

57/s

for-in

54/s

View exact numbers

Test name	Executions per second
✓ chain forEach	57 Ops/sec
for-in	54 Ops/sec

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

LLMs can make mistakes. Check important info.

Let's break down the benchmark and explain what's being tested.

**Benchmark Definition**

The provided JSON represents a JavaScript microbenchmark, specifically comparing two approaches to iterate over an array: `forEach` chaining and traditional `for-in`.

**Script Preparation Code**

The script preparation code creates a deep copy of a source object (`MyArray`) using the `Array.prototype.fill()` method. This object has several properties:

* `description`: a string
* `myNumber`: a number (123456789)
* `myBoolean`: a boolean (true)
* `jayson`: an object with two properties:
	+ `stringify`: a string referencing the `JSON.stringify()` method
	+ `parse`: a string referencing the `JSON.parse()` method

This script preparation code is executed before each test case to ensure a consistent starting point.

**Html Preparation Code**

There is no HTML preparation code provided, which means that this benchmark is focused solely on JavaScript execution performance and doesn't include any HTML-related tests.

**Individual Test Cases**

There are two test cases:

1. **chain forEach**: This test case uses the `forEach` method to iterate over the array, but with a twist: it logs each item's `myNumber` property using an arrow function (`(item) => console.log(item.myNumber);`). The goal is to measure the performance of this specific usage pattern.
2. **for-in**: This test case uses the traditional `for-in` loop to iterate over the array, logging each item's `myNumber` property.

**Library and Purpose**

The `Array.prototype.fill()` method is a built-in JavaScript library function that fills an array with a specified value. In this benchmark, it's used to create a deep copy of the source object (`MyArray`).

**Special JS Feature or Syntax**

There are no special features or syntaxes being tested in this benchmark.

**Pros and Cons of Approaches**

* **forEach chaining**: This approach can be more readable and concise, as it avoids explicit loop variables. However, it may incur additional overhead due to the arrow function syntax.
* **Traditional for-in**: This approach is more explicit and requires manual incrementation of the loop variable, but it's generally faster and more efficient.

**Other Considerations**

The benchmark focuses solely on JavaScript execution performance, which means that any performance differences are likely to be due to the iteration method used. However, other factors like memory allocation, garbage collection, and CPU overhead might also affect performance.

**Alternatives**

If you wanted to test similar benchmarks, you could explore other iteration methods, such as:

* `for` loops with explicit incrementation
* `Array.prototype.forEach()` with a callback function
* `reduce()` or `map()` methods for array operations

Keep in mind that the specific benchmarking setup and script preparation code would need to be adjusted accordingly.

Loop Comprasion (version: 0)

Comparing performance of: `chain forEach vs for-in`

Created: 2 years ago by: Guest

Go to the latest result

chain forEach

for-in

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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

Loop Comprasion (version: 0)

Comparing performance of: chain forEach vs for-in

Created: 2 years ago by: Guest

Go to the latest result

chain forEach

for-in

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: `chain forEach vs for-in`