Benchmark: querySelect speed

HTML Preparation code:

<img src="" class="slide-image-entity-a"/>
<img src="" class="slide-image-entity-b"/>
<img src="" class="slide-image-entity-c"/>

Tests:

querySelectorAll
document.querySelectorAll("img[class^='slide-image-entity'");
querySelector
document.querySelector("img[class^='slide-image-entity'");
getElementsByClassName
document.getElementsByClassName("img[class^='slide-image-entity'");

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
querySelectorAll
querySelector
getElementsByClassName

Fastest: N/A

Slowest: N/A

Latest run results:

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Autogenerated LLM Summary (model llama3.2:3b, generated one year ago):

LLMs can make mistakes. Check important info.

**What is being tested?**

The provided benchmark tests the speed of three DOM query methods: `document.querySelectorAll()`, `document.querySelector()`, and `document.getElementsByClassName()`.

These methods are used to select elements from an HTML document using CSS selectors or attribute filters. The benchmark measures how fast each method can execute a specific query on a set of images with a particular class name (`slide-image-entity`).

**Options compared:**

The three DOM query methods being tested have different approaches and trade-offs:

1. **document.querySelectorAll()**: This method returns a NodeList, which is an HTML collection of elements that match the specified CSS selector or attribute filter. It uses a combination of CSS selectors and attribute filters to narrow down the selection. The `querySelectorAll()` method can return all matching elements at once, which may be faster for large datasets.
2. **document.querySelector()**: This method returns the first element that matches the specified CSS selector or attribute filter. It is faster than `querySelectorAll()` when only one element needs to be selected.
3. **document.getElementsByClassName()**: This method returns a NodeList of elements with the specified class name (`class="slide-image-entity"`). It uses a single attribute filter, which can be slower for large datasets compared to `querySelectorAll()`.

**Pros and Cons:**

* **document.querySelectorAll()**:
	+ Pros: Can return all matching elements at once, suitable for large datasets.
	+ Cons: May require more memory, as it needs to store the entire NodeList in memory.
* **document.querySelector()**:
	+ Pros: Faster than `querySelectorAll()` when only one element is needed, and uses less memory.
	+ Cons: Only returns the first matching element, which may not be what you want if there are multiple matches.
* **document.getElementsByClassName()**:
	+ Pros: Simple to use and understand, as it only requires specifying the class name.
	+ Cons: Can be slower for large datasets due to the single attribute filter.

**Other Considerations:**

* **Browser support**: All three methods are widely supported across modern browsers. However, some older browsers might not support `querySelectorAll()` or `getElementsByClassName()`.
* **Performance implications**: The performance difference between these methods can vary depending on the specific use case and dataset size. In general, `document.querySelectorAll()` is suitable for large datasets, while `document.querySelector()` is better suited for small to medium-sized datasets.

**Library and purpose:**

None of the provided benchmark cases uses any external libraries.

No special JavaScript features or syntax are used in these test cases.

**Alternatives:**

Other DOM query methods include:

* **DocumentFragment**: Can be used to improve performance by reducing the number of DOM mutations.
* **CSSOM (CSSOM Query)**: Provides a more efficient way to select elements using CSS selectors, especially when working with large datasets.

Keep in mind that these alternative methods might not be directly comparable to the three methods tested in this benchmark.

Related benchmarks:

querySelect speed (version: 0)

test speed

Comparing performance of: querySelectorAll vs querySelector vs getElementsByClassName

Created: 2 years ago by: Guest

Jump to the latest result

querySelectorAll

querySelector

getElementsByClassName

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

No previous run results

Autogenerated LLM Summary (model llama3.2:3b, generated one year ago):