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querySelector vs getElementsByTagName check presence
(version: 0)
Comparing performance of:
querySelectorAll vs getElementsByTagName
Created:
5 years ago
by:
Guest
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HTML Preparation code:
<div></div> <div></div> <div></div> <div></div> <div></div> <div></div> <div></div> <div></div> <div></div> <div></div>
Tests:
querySelectorAll
const div = document.querySelector('div'); return div !== null;
getElementsByTagName
const allDivs = document.getElementsByTagName('div'); return allDivs.length;
Rendered benchmark preparation results:
Suite status:
<idle, ready to run>
Run tests (2)
Previous results
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Test case name
Result
querySelectorAll
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):
Let's break down the provided benchmark and explain what is tested, compared options, pros and cons of each approach, and other considerations. **Benchmark Overview** The benchmark measures the performance difference between using `document.querySelector('div')` (or its alias `querySelectorAll`) versus `document.getElementsByTagName('div')`. The test creates an HTML page with 10 `<div>` elements and checks if a specific element is present or not for both methods. **Options Compared** There are two options compared: 1. **`document.querySelector('div')`**: This method returns the first matching element within the DOM tree, starting from the root node. 2. **`document.getElementsByTagName('div')`**: This method returns a HTMLCollection containing all elements with the tag name "div". **Pros and Cons of Each Approach** * **`document.querySelector('div')`**: + Pros: Fast and efficient, especially for searching elements in a small subset of the DOM tree. + Cons: May not work as expected if there are multiple elements with the same selector, or if the element is not found (returns null). * **`document.getElementsByTagName('div')`**: + Pros: Works consistently across all browsers and versions, even when there are multiple elements with the same tag name. + Cons: May be slower than `querySelector` for large DOM trees, as it needs to scan the entire collection. **Library/Scripting Considerations** The benchmark does not use any libraries or scripting-specific features beyond JavaScript. The tests focus solely on comparing two basic DOM query methods. **Special JS Features/Syntax (None)** There are no special JavaScript features or syntax mentioned in the benchmark. Both test cases use standard JavaScript and DOM APIs. **Other Alternatives** If you were to create a similar benchmark, you could consider adding more elements, tag names, or even using CSS selectors instead of plain HTML tags. Some alternative options could include: * Using `document.querySelector()` with multiple selectors (e.g., `.class1 .class2`) * Comparing `querySelector` vs `getElementById()` * Adding a measure for `querySelectorAll()` vs `getElementsByClassName()` Keep in mind that these variations would require adjustments to the test setup and execution.
Related benchmarks:
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querySelector vs getElementsByTagName
querySelector vs getElementByTagName
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