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querySelector vs getElementsByClassName
(version: 0)
Comparing performance of:
querySelector vs getElementsByClassName
Created:
8 years ago
by:
Guest
Jump to the latest result
HTML Preparation code:
<div class="test"></div>
Tests:
querySelector
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
querySelector
getElementsByClassName
Fastest:
N/A
Slowest:
N/A
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Autogenerated LLM Summary
(model
gemma2:9b
, generated one year ago):
This benchmark tests the performance of two methods in JavaScript for selecting HTML elements: `document.querySelectorAll` and `document.getElementsByClassName`. **Options Compared:** * **`document.querySelectorAll(".test")`**: This method uses CSS selectors to select all elements with the class "test" on the page. It returns a NodeList object, which is a live collection of elements that updates when the DOM changes. * **`document.getElementsByClassName(".test")`**: This method specifically selects elements based on their class name. It returns a HTMLCollection object, similar to NodeList but not as dynamic. **Pros and Cons:** * **`querySelectorAll`**: More versatile because it supports CSS selectors for complex element selection (not just by class). Can be slower due to its flexibility. * **`getElementsByClassName`**: Simpler and often faster for basic selection by class name. Less flexible than `querySelectorAll`. **Other Considerations:** * **DOM Traversal:** Both methods involve traversing the Document Object Model (DOM), which can have performance implications depending on the size of your document. * **Live vs. Static Collections:** NodeList objects are live, meaning they update automatically if the DOM changes. HTMLCollection objects are static and don't update unless you manually refresh them. Choose based on whether you need real-time element updates. * **Alternatives:** * **`getElementById`**: If you only need to select a single element by its ID, this is the fastest option. * **DOM APIs (e.g., `closest`, `querySelectorAll` with attribute selectors):** For more complex selection scenarios based on attributes or relationships, these can be powerful alternatives. The benchmark results show that `getElementsByClassName` is generally faster than `querySelectorAll` in this specific case. However, performance can vary depending on the browser, DOM structure, and complexity of your selection criteria.
Related benchmarks:
querySelector() vs getElementsByClassName()[0]
querySelector vs getElementsByClassName()[0]
getElementsByClassName()[0] vs querySelectorAll
querySelector vs getElementsByClassName [0] with extra
querySelector vs getElementsByClassName My
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