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querySelectorAll vs getElementsByTagName with two different tag names
(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> <a></a> <a></a> <a></a> <a></a> <a></a> <a></a> <a></a> <a></a> <a></a> <a></a>
Tests:
querySelectorAll
const allDivsAndAnchors = Array.from(document.querySelectorAll('div, a')); allDivsAndAnchors.forEach(function (el) {});
getElementsByTagName
const allDivs = document.getElementsByTagName('div'); const allAnchors = document.getElementsByTagName('a'); const allDivsAndAnchors = Array.from(allDivs).concat(Array.from(allAnchors)); allDivsAndAnchors.forEach(function (el) {});
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
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Autogenerated LLM Summary
(model
llama3.2:3b
, generated one year ago):
Let's dive into the explanation of the provided benchmark. **Benchmark Overview** The benchmark compares two approaches for selecting multiple elements in HTML: `querySelectorAll` and `getElementsByTagName`. The test creates an HTML document with several `<div>` and `<a>` elements and measures which approach is faster. **Options Compared** Two options are compared: 1. **querySelectorAll**: This method selects all elements that match the specified CSS selector. In this case, it's used to select all `<div>` and `<a>` elements. 2. **getElementsByTagName**: This method returns a live HTMLCollection of all child elements that match the specified element type (in this case, `document.getElementsByTagName('div')` or `document.getElementsByTagName('a')`). The results are then concatenated using `Array.from()`. **Pros and Cons** Here's a brief overview of each approach: ### QuerySelectorAll Pros: * More flexible than `getElementsByTagName`, as it allows for more complex selectors. * Faster, since the browser can optimize the query based on the CSS selector. Cons: * Requires a compatible browser that supports the CSS selector syntax (most modern browsers do). * May have performance issues if the selection criteria is too specific or complex. ### getElementsByTagName Pros: * More straightforward and simple to use, as it only requires specifying the element type. * Works in older browsers that don't support `querySelectorAll`. Cons: * Less flexible than `querySelectorAll`, since only a single element type can be specified. * May require concatenation using `Array.from()` to combine results from multiple calls. **Library/Tool Used** None, as this is a built-in JavaScript API for web developers. **Special JS Features/Syntax** No special features or syntax are used in the benchmark. The test only relies on standard JavaScript and HTML elements. **Other Alternatives** If you need to compare performance of other selection methods, here are some alternatives: * `querySelector`: Similar to `querySelectorAll`, but returns a single element instead of all matching elements. * `getElementsByClassName` (not shown in this benchmark): Selects elements by their class names. * `querySelectorAll([selector1, selector2])`: Allows for multiple selectors to be combined using the `||` operator. These alternatives can be used to compare performance with different selection methods, such as: * Using a single element type with `getElementsByTagName` * Combining two or more CSS selectors with `querySelector` Keep in mind that each approach has its strengths and weaknesses, and some may perform better for specific use cases. The benchmark provides a useful comparison of these approaches, but you should consider the specific requirements of your project when choosing an implementation.
Related benchmarks:
querySelector vs. getElementsByClassName nested dom
querySelectorAll() vs getElementsByTagName()
querySelectorAll() vs getElementsByTagName() - with constant
querySelectorAll() vs getElementsByTagName() - with constant length
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