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querySelector vs querySelectorAll vs getElementsByClassName vs querySelector (ID) vs getElementsByID with lots of elements
(version: 0)
Comparing performance of:
querySelector vs querySelectorAll vs getElementsByClassName vs querySelector (ID) vs getElementsByID
Created:
3 years ago
by:
Guest
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HTML Preparation code:
<div class="test" id="test"></div><div class="test" id="test1"></div><div class="test" id="test1"></div><div class="test" id="test1"></div><div class="test" id="test1"></div><div class="test" id="test1"></div><div class="test" id="test1"></div><div class="test" id="test1"></div><div class="test" id="test1"></div><div class="test" id="test1"></div><div class="test" id="test1"></div><div class="test" id="test1"></div><div class="test" id="test1"></div><div class="test" id="test1"></div><div class="test" id="test1"></div><div class="test" id="test1"></div><div class="test" id="test1"></div><div class="test" id="test1"></div><div class="test" id="test1"></div><div class="test" id="test1"></div><div class="test" id="test1"></div><div class="test" id="test1"></div><div class="test" id="test1"></div><div class="test" id="test1"></div><div class="test" id="test1"></div><div class="test" id="test1"></div><div class="test" id="test1"></div><div class="test" id="test1"></div><div class="test" id="test1"></div><div class="test" id="test1"></div><div class="test" id="test1"></div><div class="test" id="test1"></div><div class="test" id="test1"></div><div class="test" id="test1"></div><div class="test" id="test1"></div><div class="test" id="test1"></div><div class="test" id="test1"></div><div class="test" id="test1"></div><div class="test" id="test1"></div><div class="test" id="test1"></div><div class="test" id="test1"></div><div class="test" id="test1"></div><div class="test" id="test1"></div><div class="test" id="test1"></div><div class="test" id="test1"></div><div class="test" id="test1"></div><div class="test" id="test1"></div><div class="test" id="test1"></div><div class="test" id="test1"></div><div class="test" id="test1"></div>
Tests:
querySelector
document.querySelector(".test")
querySelectorAll
document.querySelectorAll(".test")
getElementsByClassName
document.getElementsByClassName(".test")
querySelector (ID)
document.querySelector("#test")
getElementsByID
document.getElementById("test")
Rendered benchmark preparation results:
Suite status:
<idle, ready to run>
Run tests (5)
Previous results
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Test case name
Result
querySelector
querySelectorAll
getElementsByClassName
querySelector (ID)
getElementsByID
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 dive into the explanation of the provided benchmark. **Benchmark Definition** The benchmark tests four different ways to select HTML elements from a DOM tree: `document.querySelector`, `document.querySelectorAll`, `document.getElementsByClassName`, and `document.getElementById`. There are two variations of each method: 1. Without an ID attribute (e.g., `.test`) 2. With an ID attribute (e.g., `#test`) **Options Compared** The benchmark compares the performance of these four methods with their respective ID-based variants. * `querySelector` vs `querySelectorAll` + `querySelector` is used to select a single element based on a CSS selector. + `querySelectorAll` returns all elements that match the CSS selector, even if only one element exists. * `getElementsByClassName` vs `document.getElementById` + `getElementsByClassName` returns a live HTMLCollection of elements with the specified class name. + `document.getElementById` returns a single element with the specified ID attribute. **Pros and Cons** Here's a brief summary of each method: 1. **`document.querySelector`**: Fast, but can return null if no matching element is found. 2. **`document.querySelectorAll`**: Can be slow for large number of matching elements, as it returns a live HTMLCollection. 3. **`getElementsByClassName`**: Returns all elements with the specified class name, which can be useful when multiple classes are used. 4. **`document.getElementById`**: Fast and efficient, but only works with ID attributes. **Other Considerations** * `querySelectorAll` is slower than other methods for large numbers of matching elements because it has to parse the entire DOM tree. * `getElementsByClassName` can be slower than `document.querySelector` if no elements have the specified class name. **Library and Syntax** None of the benchmarked methods use external libraries. However, some browsers may use polyfills or native implementations for these APIs. **Special JS Features** There are no special JavaScript features used in this benchmark. **Alternatives** Other alternatives to test might include: 1. Using `document.querySelectorAll` with a more specific selector (e.g., `.test:contains("hello")`) to test its performance. 2. Adding more elements to the DOM tree using JavaScript to increase the number of matching elements for `getElementsByClassName`. 3. Using a different browser or version to compare performance across different platforms. Overall, this benchmark provides a good starting point to understand the relative performance of these four methods in selecting HTML elements from the DOM tree.
Related benchmarks:
Get element by ID: jQuery vs getElementById vs querySelector
querySelector vs getElementById & getElementsByClassName
querySelector vs querySelectorAll vs getElementsByClassName vs querySelector (ID) vs getElementByID
querySelector vs querySelectorAll vs getElementsByClassName vs querySelector (ID) vs getElementsByID 20x
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