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querySelector vs getElementById
(version: 0)
Test the performance of the default Javascript querySelector vs the getElementById method.
Comparing performance of:
querySelector vs getElementsByClassName
Created:
9 years ago
by:
Guest
Go to the latest result
HTML Preparation code:
<html> <body> <div class="foo" id="test2"></div> <div class="foo2" id="test"></div> </body> </html>
Tests:
querySelector
document.querySelector(".foo");
getElementsByClassName
document.getElementsByClassName('foo');
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
Latest run results:
Run details:
(Test run date:
one year ago
)
User agent:
Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/135.0.0.0 Safari/537.36
Browser/OS:
Chrome 135 on Windows
View result in a separate tab
Embed
Embed Benchmark Result
<iframe src="https://measurethat.net/Embed?id=600636" width="100%" height="500px"></iframe>
getElementsByClassName
9.7M/s
querySelector
6.3M/s
View exact numbers
Test name
Executions per second
✓
getElementsByClassName
9,684,943 Ops/sec
querySelector
6,284,561 Ops/sec
Autogenerated LLM Summary
(model
llama3.2:3b
, generated one year ago):
Let's break down the provided benchmark. **What is tested?** The benchmark compares two DOM query methods: `querySelector` and `getElementsByClassName`. The test case uses HTML elements with both class attributes (e.g., `.foo`) and IDs (e.g., `test2`, `test`). The goal is to measure the performance of these methods in retrieving elements from the document. **Options compared** Two options are compared: 1. **`querySelector`**: This method is a part of the DOM Standard (ECMAScript 5) and allows selecting elements based on their class name, tag name, ID, or attribute values. 2. **`getElementsByClassName`**: This method is also part of the DOM Standard (ECMAScript 4) and retrieves all elements with a specified class name. **Pros and cons** * `querySelector`: + Pros: more flexible and powerful, can be used to select multiple elements based on different criteria. + Cons: might have higher overhead due to its flexibility, as it needs to parse the CSS selector string. * `getElementsByClassName`: + Pros: simpler and faster, as it only retrieves elements with a specific class name. + Cons: less flexible, as it cannot be used to select multiple elements based on different criteria. **Library** In this benchmark, none of the libraries are explicitly mentioned. However, the use of `querySelector` suggests that the browser supports ECMAScript 5 and its DOM Standard. **Special JS feature or syntax** The test case uses a CSS selector string in the `querySelector` method (e.g., `"document.querySelector(".foo")"`). This is a feature introduced in ECMAScript 5, allowing JavaScript to use CSS-like selectors for DOM querying. The `getElementsByClassName` method also relies on this feature. **Other alternatives** If you want to test alternative methods for selecting elements, you could consider the following: * **`getElementsByTagName`**: Retrieves all elements with a specified tag name (e.g., `"document.getElementsByTagName('div')"`). * **`querySelectorAll`**: Similar to `querySelector`, but returns an HTMLCollection that contains all matching elements.
Related benchmarks
querySelector() vs getElementsByClassName()[0]
querySelector vs getElementById & getElementsByClassName
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getElementsByClassName()[0] vs querySelectorAll
getElementById VS querySelector (simple comparison)
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