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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:
6 years ago
by:
Guest
Jump to the latest result
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>
Run tests (4)
Previous results
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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:
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Autogenerated LLM Summary
(model
llama3.2:3b
, generated one year ago):
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.
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