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Comparison with className vs classList with unique value
(version: 0)
Comparing performance of:
classList with unique class vs className vs classList with multiple classes
Created:
6 years ago
by:
Guest
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HTML Preparation code:
<div id="foo" class="test"></div>
Tests:
classList with unique class
var element = document.getElementById("foo"); var i = 1000; while (i--) { if(element.classList == 'test') { console.log('Equal'); } }
className
var element = document.getElementById("foo"); var i = 1000; while (i--) { if(element.className == 'test') { console.log('Equal'); } }
classList with multiple classes
var element = document.getElementById("foo"); var i = 1000; while (i--) { if(element.classList.contains('test')) { console.log('Contains'); } }
Rendered benchmark preparation results:
Suite status:
<idle, ready to run>
Run tests (3)
Previous results
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Test case name
Result
classList with unique class
className
classList with multiple classes
Fastest:
N/A
Slowest:
N/A
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Autogenerated LLM Summary
(model
llama3.2:3b
, generated one year ago):
Let's break down the benchmark and explain what's being tested. **Benchmark Purpose:** The benchmark is designed to compare the performance of three different ways to check if an element has a specific class in JavaScript, using the `classList` API (a part of HTML5). The tests aim to determine which approach is fastest for checking equality (i.e., whether the class exists exactly once) and containment (i.e., whether the class is among a set of classes). **Options being compared:** 1. **`element.classList == 'test'`**: This method checks if the `classList` property contains the exact string `'test'`. However, this approach has some issues: * It's not very efficient because it creates a new RegExp object every time the test is run. * It doesn't handle cases where the class name might contain special characters or whitespace. 2. **`element.className == 'test'`**: This method checks if the `className` property (a string) contains the exact string `'test'`. However, this approach has some issues: * It's not very efficient because it creates a new RegExp object every time the test is run. * It doesn't handle cases where the class name might contain special characters or whitespace. 3. **`element.classList.contains('test')`**: This method checks if the `classList` property contains the exact string `'test'`. However, this approach has some issues: * It's not very efficient because it uses a linear search algorithm. * It doesn't handle cases where the class name might contain special characters or whitespace. **Pros and Cons:** 1. **`element.classList == 'test'`**: * Pros: Simple and easy to understand. * Cons: Inefficient, prone to errors with special characters or whitespace, and not designed for containment checks. 2. **`element.className == 'test'`**: * Pros: Similar to the first option in terms of simplicity and ease of use. * Cons: Same issues as the first option (inefficiency, potential errors, and lack of support for containment). 3. **`element.classList.contains('test')`**: * Pros: Designed for containment checks, efficient in practice (algorithms with a time complexity of O(n)), and handles special characters or whitespace. * Cons: Less straightforward than the first two options. **Library usage:** In this benchmark, no specific library is used. However, the `classList` API is a built-in feature of HTML5 that allows you to dynamically add and remove classes from an element's class list. **Special JS features or syntax:** The only special aspect of JavaScript in this benchmark is the use of template literals (the `\r\n`) and the implicit coercion of strings (`'test'`). **Alternatives:** Other approaches for checking if an element has a specific class might include: * Using `element.classList.contains('class-name')` * Creating a regular expression that matches the expected class names * Using a third-party library or function that provides efficient class name checking Keep in mind that these alternatives may have different trade-offs and performance characteristics compared to the options being tested.
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