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querySelectorAll vs. getElementsByClassName bug patch
(version: 0)
Comparing performance of:
querySelectorAll vs getElementsByClassName
Created:
5 years ago
by:
Guest
Jump to the latest result
HTML Preparation code:
<div class="test"></div>
Tests:
querySelectorAll
document.querySelectorAll(".test")
getElementsByClassName
document.getElementsByClassName("test")
Rendered benchmark preparation results:
Suite status:
<idle, ready to run>
Run tests (2)
Previous results
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Test case name
Result
querySelectorAll
getElementsByClassName
Fastest:
N/A
Slowest:
N/A
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Autogenerated LLM Summary
(model
llama3.2:3b
, generated one year ago):
Let's dive into the world of MeasureThat.net and explore what's being tested in this benchmark. **Benchmark Overview** The benchmark is designed to compare the performance of two DOM selection methods: `querySelectorAll` and `getElementsByClassName`. The test case uses an HTML element with a class attribute named "test". **Options Compared** Two options are compared: 1. **`document.querySelectorAll(".test")`**: This method returns a NodeList containing all elements that match the specified CSS selector, ".test". It's a more modern and efficient approach to selecting DOM elements. 2. **`document.getElementsByClassName("test")`**: This method returns an HTMLCollection containing all elements that match the specified class name, "test". Although this method was widely used in the past, it has been deprecated since ECMAScript 5 (2009) and replaced by `querySelectorAll`. **Pros and Cons** **`document.querySelectorAll(".test")`:** Pros: * More efficient than `getElementsByClassName` (less CPU cycles) * Less prone to false positives (e.g., selecting elements with other class names) * Compatible with modern browsers Cons: * May have slower performance in older browsers that don't support it * Requires a CSS selector, which can be less intuitive for beginners **`document.getElementsByClassName("test")`:** Pros: * Widely supported across older browsers (IE 8+, Firefox 3.5+) * Can be used with inline styles or attributes that contain class names Cons: * More CPU-intensive and slower than `querySelectorAll` * Prone to false positives if the element has other class names * Depreciated since ECMAScript 5, so it's not recommended for new development. **Library Usage** None of the test cases use a library or any external dependencies. **Special JS Feature/Syntax** There is no special JavaScript feature or syntax being tested in this benchmark. The focus is solely on comparing the performance of two DOM selection methods. **Other Alternatives** If you want to create similar benchmarks, consider testing other DOM selection methods, such as: * `document.querySelector(".test")` (a more concise alternative to `querySelectorAll`) * `document.getElementsByTagName("div")[0].classList.contains("test")` (using the `contains` method with an element's class list) * `document.querySelectorAll("[class='test']")` (selecting elements by attribute) Keep in mind that these alternatives may have different performance characteristics and should be tested accordingly.
Related benchmarks:
getElementsByClassName()[0] vs querySelectorAll
[Fixed] querySelectorAll vs. getElementsByClassName
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