Benchmark: querySelector test (deeper faster?)

HTML Preparation code:

<html>
    <body>
        <div id="test2"></div>
        <div id="test"></div>
    </body>
</html>

Tests:

querySelector deep
document.querySelector("body > div#test");
querySelector
document.querySelector("#test");
getElementById
document.getElementById("test");

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
querySelector deep
querySelector
getElementById

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 2 years ago)

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/105.0.0.0 Safari/537.36

Browser/OS: Chrome 105 on Mac OS X 10.15.7

View result in a separate tab

Test name	Executions per second
querySelector deep	3765453.8 Ops/sec
querySelector	5159416.5 Ops/sec
getElementById	7906806.5 Ops/sec

Autogenerated LLM Summary (model llama3.2:3b, generated 6 months ago):

LLMs can make mistakes. Check important info.

**Benchmark Analysis**

The provided benchmark measures the performance of three different methods to select an HTML element: `querySelector`, `querySelector` with a deep selector, and `getElementById`. The goal is to determine which method is faster.

**Options Compared**

1. **`querySelector`**: This method uses CSS selectors to find an element in the DOM.
2. **`querySelector` (deep)**: This variant uses a deeper CSS selector to traverse the DOM tree from the root element.
3. **`getElementById`**: This method uses the `id` attribute of the HTML element to identify it.

**Pros and Cons**

*   **`querySelector` and `querySelector` (deep)**:
    *   Pros: These methods are generally faster and more flexible than `getElementById`, as they can use CSS selectors to target elements based on their properties, classes, or attributes.
    *   Cons: These methods may be slower for very deep selector expressions or when the DOM is not optimized for fast traversal. They also require a good understanding of CSS selectors, which can add complexity and make debugging harder.
*   **`getElementById`**:
    *   Pros: This method is generally faster than `querySelector` and `querySelector` (deep), as it only requires finding an element with a specific `id`. It's also simpler to understand and use, especially for simple cases.
    *   Cons: This method has limitations, such as the need to explicitly specify the `id` attribute of the HTML element, which can be lost during DOM manipulation. Additionally, using `getElementById` can lead to slower performance if the DOM is not optimized for fast lookup.

**Library and Purpose**

*   **`querySelector` and `querySelector` (deep)**: These methods use the W3C DOM API, specifically the `querySelector` and `querySelector` selectors. The purpose of these APIs is to provide a way to select and manipulate elements in the DOM using CSS-like selectors.
*   **`getElementById`**: This method uses the W3C DOM API's `getElementById` method, which returns the element with the specified `id`.

**Special JS Feature/Syntax**

There are no special JavaScript features or syntax mentioned in this benchmark.

**Alternative Approaches**

Other alternatives for selecting elements include:

*   **`getElementsByTagName`**: This method returns an HTMLCollection of all elements with the specified tag name.
*   **`getElementsByClassName`**: This method returns a NodeList of all elements with the specified class name.
*   **`getElementsByAttribute`**: This method returns a NodeList of all elements with the specified attribute.

These methods can be useful in specific situations, but they often have performance implications compared to `querySelector` and `querySelector` (deep).

Related benchmarks:

querySelector test (deeper faster?) (version: 0)

querySelector deeper vs querySelector vs getElementById

Comparing performance of: querySelector deep vs querySelector vs getElementById

Created: 3 years ago by: Registered User

Jump to the latest result

querySelector deep

querySelector

getElementById

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 6 months ago):