Benchmark: for lef of OR for var of OR for var length - v2

HTML Preparation code:

<div class="list-container">
  <div class="list-item"></div>
  <div class="list-item"></div>
  <div class="list-item"></div>
  <div class="list-item"></div>
  <div class="list-item"></div>
</div>

Script Preparation code:

var $allItens = document.getElementsByClassName('list-item');

Tests:

for lef of
for (let $item of $allItens) { console.log($item); }
for var of
for (var $item of $allItens) { console.log($item); }
for var(out) length
var i = 0; for (i; i < $allItens.length; i++) { console.log($allItens[i]); }
for var(inside) length
for (var i = 0; i < $allItens.length; i++) { console.log($allItens[i]); }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
for lef of
for var of
for var(out) length
for var(inside) length

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 5 years ago)

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/75.0.3770.100 Safari/537.36

Browser/OS: Chrome 75 on Windows

View result in a separate tab

Test name	Executions per second
for lef of	20805.1 Ops/sec
for var of	21798.8 Ops/sec
for var(out) length	23411.1 Ops/sec
for var(inside) length	23352.6 Ops/sec

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

LLMs can make mistakes. Check important info.

Let's break down the provided benchmark and its test cases.

**Benchmark Overview**

The benchmark, named "for lef of OR for var of OR for var length - v2", compares different approaches to iterating over an array of elements in JavaScript. The benchmark uses a specific HTML structure with 5 list items, which is retrieved using `document.getElementsByClassName('list-item')`.

**Test Cases**

There are four test cases:

1. **`for (let $item of $allItens) {\r\n    console.log($item);\r\n}`**: This test case uses the `for...of` loop with a let variable `$item`. The `for...of` loop is a modern JavaScript syntax that iterates over arrays and iterable objects.
2. **`for (var $item of $allItens) {\r\n    console.log($item);\r\n}`**: This test case uses the `for...of` loop with a var variable `$item`. Note that `var` is not recommended for use in modern JavaScript, as it can lead to unexpected scope and closure issues.
3. **`var i = 0;\r\nfor (i; i < $allItens.length; i++) {\r\n    console.log($allItens[i]);\r\n}`**: This test case uses a traditional `for` loop with an incrementing counter variable `$i`. The loop iterates over the array using the length property.
4. **`for (var i = 0; i < $allItens.length; i++) {\r\n    console.log($allItens[i]);\r\n}`**: This test case uses a traditional `for` loop with an incrementing counter variable `$i`. The loop iterates over the array using the length property.

**Library and Special Features**

* None of these test cases use any external libraries.
* Note that the `let` keyword is used in the first two test cases, which is a modern JavaScript feature introduced in ECMAScript 2015 (ES6). The `var` keyword is not recommended for use with let or const variables, as it can lead to unexpected scope and closure issues.

**Pros and Cons**

* **`for...of` loop**: Pros:
	+ More concise and expressive syntax.
	+ Automatic iteration over arrays and iterable objects.
	+ Less prone to errors compared to traditional `for` loops.
* Cons:
	+ Not supported in older JavaScript engines (e.g., Internet Explorer).
	+ May not work as expected with certain types of data (e.g., null, undefined).
* **Traditional `for` loop**: Pros:
	+ Widely supported across all JavaScript engines.
	+ Can be more efficient for large datasets.
* Cons:
	+ More verbose and error-prone syntax.
	+ Requires manual iteration over the array.

**Other Alternatives**

If you're interested in exploring alternative approaches, consider using other methods such as:

* Array.prototype.forEach(): a method that iterates over an array, calling a provided callback function for each element.
* Array.prototype.map(): a method that creates a new array with transformed values from an original array.
* Array.prototype.filter(): a method that creates a new array with elements that pass a test provided by a function.

These alternatives can provide more flexibility and control over the iteration process, but may also add complexity to your code.

Related benchmarks:

for lef of OR for var of OR for var length - v2 (version: 0)

Comparing performance of: for lef of vs for var of vs for var(out) length vs for var(inside) length

Created: 5 years ago by: Guest

Jump to the latest result

for lef of

for var of

for var(out) length

for var(inside) length

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

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