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querySelector vs getElementsByClassName on multiple elements
(version: 0)
Comparing performance of:
querySelector vs getElementsByClassName
Created:
4 years ago
by:
Guest
Go to the latest result
HTML Preparation code:
<div class="test"></div> <div class="test"></div> <div class="test"></div>
Tests:
querySelector
document.querySelector(".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
Latest run results:
Run details:
(Test run date:
28 days ago
)
User agent:
Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:152.0) Gecko/20100101 Firefox/152.0
Browser/OS:
Firefox 152 on Windows
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Embed Benchmark Result
<iframe src="https://measurethat.net/Embed?id=632973" width="100%" height="500px"></iframe>
getElementsByClassName
6.1M/s
querySelector
3.3M/s
View exact numbers
Test name
Executions per second
✓
getElementsByClassName
6,090,387 Ops/sec
querySelector
3,318,362 Ops/sec
Autogenerated LLM Summary
(model
llama3.2:3b
, generated one year ago):
Let's break down the provided benchmark and explain what's being tested, compared, and its pros and cons. **Benchmark Definition** The benchmark compares two methods for selecting elements in an HTML document: 1. `document.querySelector(".test")` 2. `document.getElementsByClassName("test")` These methods are used to retrieve a single element or all elements that match the specified class name. **Options Compared** The two options being compared are: 1. **`querySelector`**: This method returns the first element that matches the specified selector (in this case, `.test`). If no matching element is found, it returns `null`. 2. **`getElementsByClassName`**: This method returns a live HTMLCollection of all elements that have the specified class name. **Pros and Cons** * **QuerySelector**: * Pros: * More efficient and faster compared to `getElementsByClassName`, especially for modern browsers. * Returns only the first matching element, which can be beneficial when you're looking for a specific node. * Cons: * May return `null` if no elements match the selector. * **getElementsByClassName**: * Pros: * Returns all elements that match the class name, which can be useful in certain scenarios. * Works even if there's only one element with the specified class name. * Cons: * Generally slower and more resource-intensive than `querySelector`. * May return multiple elements if there are multiple elements with the same class name. **Library Usage** In this benchmark, no specific library is used. The `document` object is used to access the DOM (Document Object Model) of an HTML document. **Special JS Feature/Syntax** There's a special syntax being tested here - the use of class names instead of IDs or tags for element selection. This is a common pattern in web development, especially when working with classes that can be dynamically added or removed from elements. **Other Alternatives** If you need to select elements based on different criteria, other methods you might consider using include: * `querySelectorAll()`: Returns a NodeList of all matching elements. * `getElementById()`: Returns the element with the specified ID. * `getElementsByTagName()` and friends: Return HTMLCollections or NodeLists of elements that match certain tags or attributes. Keep in mind that these methods may have different performance characteristics, return types, or usage patterns compared to `querySelector` and `getElementsByClassName`. Let me know if you'd like further clarification on any aspect!
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