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DOM traversal Compare
(version: 0)
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Comparing performance of:
querySelectorAll vs getElementsByClassName vs getElementsByTagName
Created:
4 years ago
by:
Guest
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HTML Preparation code:
<p class="foo"></p> <p class="foo"></p> <p class="foo"></p> <p class="foo"></p> <p class="foo"></p> <p class="foo"></p> <p class="foo"></p> <p class="foo"></p> <p class="foo"></p> <p class="foo"></p> <p class="foo"></p> <p class="foo"></p> <p class="foo"></p> <p class="foo"></p> <p class="foo"></p> <p class="foo"></p> <p class="foo"></p> <p class="foo"></p> <p class="foo"></p> <p class="foo"></p>
Tests:
querySelectorAll
document.querySelectorAll('.foo')
getElementsByClassName
document.getElementsByClassName('foo')
getElementsByTagName
document.getElementsByTagName('p')
Rendered benchmark preparation results:
Suite status:
<idle, ready to run>
Run tests (3)
Previous results
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Test case name
Result
querySelectorAll
getElementsByClassName
getElementsByTagName
Fastest:
N/A
Slowest:
N/A
Latest run results:
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Autogenerated LLM Summary
(model
llama3.2:3b
, generated one year ago):
**Benchmark Explanation** The provided benchmark measures the performance of three DOM traversal methods in JavaScript: `querySelectorAll`, `getElementsByClassName`, and `getElementsByTagName`. The test case uses an HTML structure with 10 identical elements, each with a class "foo". **Options Comparison** 1. **`querySelectorAll('.foo')`**: This method selects all elements with the exact class name "foo". It is considered fast because it allows the browser to use its internal CSS parser and DOM caching. * Pros: Fast, efficient, and widely supported. * Cons: May not match exactly with CSS selectors, can be slower for complex queries. 2. **`document.getElementsByClassName('foo')`**: This method returns a live HTMLCollection of all elements with the class "foo". It is considered slow because it requires the browser to scan the DOM tree for matching elements, which can be time-consuming. * Pros: Simple and easy to understand, but slower than `querySelectorAll`. * Cons: Can be slower, less efficient than `querySelectorAll`, and may cause performance issues in complex scenarios. 3. **`document.getElementsByTagName('p')`**: This method returns a live HTMLCollection of all elements with the tag name "p". It is considered slow because it requires the browser to scan the DOM tree for matching elements with a specific tag name, which can be time-consuming. * Pros: Simple and easy to understand, but slower than `querySelectorAll`. * Cons: Can be slower, less efficient than `querySelectorAll`, and may cause performance issues in complex scenarios. **Library Considerations** None of the test cases use any external libraries. The benchmark focuses solely on the built-in DOM traversal methods provided by JavaScript. **Special JS Feature/Syntax** There is no special JavaScript feature or syntax used in this benchmark. All tests rely on standard ECMAScript features and do not utilize experimental or proprietary APIs. **Other Alternatives** 1. **`querySelector('p.foo')`**: This method selects an element with the tag name "p" that has a descendant with class "foo". It is considered fast because it allows the browser to use its internal CSS parser and DOM caching. 2. **`document.querySelector('.foo')`**: This method returns the first matching element with the class "foo" in the document. It is considered slower than `querySelectorAll` due to the need for a more complex query. 3. **`getElementsByTagName('p')`** ( deprecated ): This method was previously used for selecting elements with the tag name "p", but it has been deprecated in favor of `getElementsByTagName`. Note: The performance differences between these alternatives may vary depending on the specific use case, browser version, and platform.
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