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querySelector vs getElementsByClassName _2 (Get first element)
(version: 0)
Comparing performance of:
querySelector vs getElementsByClassName vs getElementsByClassName (item)
Created:
6 years ago
by:
Guest
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HTML Preparation code:
<div class="test"></div> <div class="test"></div> <div class="test"></div> <div class="test"></div> <div class="test"></div> <div class="test"></div> <div class="test"></div> <div class="test"></div> <div class="test"></div> <div class="test"></div> <div class="test"></div> <div class="test"></div> <div class="test"></div> <div class="test"></div> <div class="test"></div> <div class="test"></div> <div class="test"></div> <div class="test"></div> <div class="test"></div> <div class="test"></div> <div class="test"></div> <div class="test"></div> <div class="test"></div> <div class="test"></div> <div class="test"></div> <div class="test"></div> <div class="test"></div> <div class="test"></div> <div class="test"></div> <div class="test"></div> <div class="test"></div> <div class="test"></div> <div class="test"></div> <div class="test"></div> <div class="test"></div> <div class="test"></div> <div class="test"></div> <div class="test"></div> <div class="test"></div> <div class="test"></div> <div class="test"></div> <div class="test"></div> <div class="test"></div> <div class="test"></div> <div class="test"></div> <div class="test"></div> <div class="test"></div> <div class="test"></div> <div class="test"></div> <div class="test"></div> <div class="test"></div> <div class="test"></div> <div class="test"></div> <div class="test"></div> <div class="test"></div>
Tests:
querySelector
document.querySelector(".test")
getElementsByClassName
document.getElementsByClassName(".test")[0]
getElementsByClassName (item)
document.getElementsByClassName(".test").item(0);
Rendered benchmark preparation results:
Suite status:
<idle, ready to run>
Run tests (3)
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Test case name
Result
querySelector
getElementsByClassName
getElementsByClassName (item)
Fastest:
N/A
Slowest:
N/A
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Autogenerated LLM Summary
(model
llama3.2:3b
, generated one year ago):
Let's break down the provided benchmark JSON and explain what is being tested, compared, and their pros and cons. **Benchmark Definition** The benchmark defines two main test cases: 1. `document.querySelector(".test")` 2. `document.getElementsByClassName(".test")[0]` 3. `document.getElementsByClassName(".test").item(0);` All three test cases are designed to retrieve the first element with the class "test" from an HTML document. **Script Preparation Code** The script preparation code is empty, which means that the benchmark assumes the test HTML document is provided as part of the `Html Preparation Code`. **Html Preparation Code** The `Html Preparation Code` contains a repeated sequence of five `<div>` elements with the class "test", ensuring that there are enough elements for the querySelector and getElementsByClassName functions to operate on. **What's being tested?** * **QuerySelector**: The `document.querySelector(".test")` function is being tested, which returns the first element matching the specified CSS selector. In this case, it will return one of the five `<div>` elements with the class "test". * **getElementsByClassName**: The `document.getElementsByClassName(".test")[0]` function is being tested, which returns an array of all elements with the specified class name. In this case, it will return an array containing all five `<div>` elements with the class "test". * **getElementsByClassName (item)**: The `document.getElementsByClassName(".test").item(0)` function is being tested, which returns the first element in the resulting array from getElementsByClassName. In this case, it will return one of the five `<div>` elements with the class "test". **Options compared** The benchmark compares three different approaches: * **QuerySelector**: Returns the first matching element + Pros: Simple and efficient, suitable for most use cases. + Cons: May not be as flexible or powerful as other methods (e.g., getElementsByClassName). * **getElementsByClassName**: Returns an array of all matching elements + Pros: More flexible and powerful than QuerySelector, can handle multiple matches. + Cons: Returns an array, which may require additional processing to extract the first element. * **getElementsByClassName (item)**: Returns the first element in the resulting array from getElementsByClassName + Pros: Convenient way to get the first matching element without having to process the entire array. + Cons: May be slower than QuerySelector for most use cases. **Library** There is no explicit library mentioned in the benchmark definition. However, it's worth noting that both `querySelector` and `getElementsByClassName` are part of the W3C DOM API, which is a standardized set of APIs for manipulating HTML documents. **Special JS feature or syntax** None of the test cases utilize any special JavaScript features or syntax beyond what is standard in modern JavaScript.
Related benchmarks:
querySelector vs getElementsByClassName with multiple matching nodes
querySelectorAll vs getElementsByClassName Test
querySelectorAll vs getElementsByClassName Test2
querySelector vs querySelectorAll simple (single element result)
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