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getElementByID vs querySelector vs firstChild walk
(version: 0)
fastest way to select a dom node
Comparing performance of:
firstChild attr vs querySelector attr vs getElementbyId
Created:
2 years ago
by:
Registered User
Jump to the latest result
HTML Preparation code:
<div id="app" pico-id="app">Runtime Runtime is the best ever. 4<p class="square" pico-id="$P0">bencmarking: Runtime Total time: 5.00ms<br>Mouse: x = 0, y = 0</p> <p>you have <strong class="blue" pico-id="S0">4</strong> likes!! and <b pico-id="B0">3</b> items.</p><button style="background-color: #f31261; cursor: pointer; display: block; color:white;" pico-id="$B0"><span pico-id="SN1">0-1--1</span></button> <div class="form-group"><label class="form-label">Name</label><input class="form-input " type="text" placeholder="Press enter key to submit a todo" pico-id="I0"> <p><strong pico-id="S1"> : 0</strong></p> </div><strong pico-id="$S2">Currently selected: </strong> <p>Your character is <em pico-id="E0">Your Pokemon Level has found a trainer</em></p> <div class="btn-group btn-group-block"><button class="btn btn-primary" pico-id="B1">+Likes</button><button class="btn btn-primary" pico-id="B2">-Dislikes</button></div> <div class="btn-group btn-group-block iter-tools"><button class="btn" pico-id="B3">Prepend Todos <span pico-id="S2">4</span></button></div> </div>
Script Preparation code:
var app = document.getElementById('app')
Tests:
firstChild attr
var spanTxt = app.firstChild.nextSibling.nextSibling.nextSibling.nextSibling.nextSibling.nextSibling.nextSibling.nextSibling.nextSibling.nextSibling.firstChild
querySelector attr
var spanTxt = document.querySelector('[pico-id="S2"]')
getElementbyId
var spanTxt = document.getElementById('S2')
Rendered benchmark preparation results:
Suite status:
<idle, ready to run>
Run tests (3)
Previous results
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Test case name
Result
firstChild attr
querySelector attr
getElementbyId
Fastest:
N/A
Slowest:
N/A
Latest run results:
Run details:
(Test run date:
10 months ago
)
User agent:
Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:139.0) Gecko/20100101 Firefox/139.0
Browser/OS:
Firefox 139 on Windows
View result in a separate tab
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Embed Benchmark Result
<iframe src="https://measurethat.net/Embed?id=610553" width="100%" height="500px"></iframe>
Test name
Executions per second
firstChild attr
855234368.0 Ops/sec
querySelector attr
1848629.5 Ops/sec
getElementbyId
5234814.0 Ops/sec
Autogenerated LLM Summary
(model
llama3.2:3b
, generated one year ago):
**Overview of the Benchmark** The provided JSON represents a JavaScript microbenchmarking test on MeasureThat.net. The goal is to determine the fastest way to select a DOM node in a given HTML document. **Options Compared** Three options are compared: 1. **firstChild**: This method traverses the DOM tree starting from the first child of an element until it finds the target node. 2. **querySelector**: This method allows querying the DOM using a CSS selector, which can be more efficient than traversing the tree. 3. **getElementById**: This method retrieves an element by its ID attribute. **Pros and Cons** * **firstChild**: Pros: * Fast for simple cases with direct descendants * Can work well with complex DOM structures if the target node is not too deep down the tree * * Cons: * May be slow for deeply nested or dynamically generated content * May require more memory allocation and garbage collection due to traversal * **querySelector**: Pros: * Fast for simple cases with direct descendants * Supports advanced CSS selectors, making it suitable for complex layouts * * Cons: * May be slower than `firstChild` or `getElementById` for very deep or nested content * Requires a valid CSS selector syntax * **getElementById**: Pros: * Fast for simple cases with direct descendants * Supports accessing elements by their unique ID attribute * * Cons: * May be slower than `querySelector` or `firstChild` for complex layouts * Requires a valid element ID **Library and Syntax** The provided code uses the following libraries: * **Document.getElementById()**: A built-in JavaScript method for retrieving an element by its ID attribute. * **document.querySelector()**: A modern JavaScript method introduced in ECMAScript 2015 (ES6) for querying the DOM using a CSS selector. No other special JavaScript features or syntax are mentioned. However, it's worth noting that the `querySelector` method supports advanced selectors like `:nth-child`, `:hover`, and more, which can greatly impact performance and readability depending on use cases. **Other Alternatives** If you're looking for alternative methods to select DOM nodes: * **`document.querySelectorAll()`**: Returns a NodeList containing all matching elements. It's similar to `querySelector` but returns multiple results. * **`Array.from()`**: Converts an HTMLCollection or NodeList into an array. This can be useful when working with modern JavaScript APIs. When choosing the right method for DOM selection, consider factors such as performance, code readability, and support for different browsers and versions of JavaScript. In conclusion, understanding how to select DOM nodes efficiently using `firstChild`, `querySelector`, and `getElementById` is crucial for optimizing web applications. By considering pros, cons, and potential alternatives, developers can choose the best approach for their specific use cases.
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