Benchmark: querySelector with html tag vs querySelector only class

HTML Preparation code:

<div class="js-test"></div>

Tests:

querySelector with html tag
var $el = document.querySelector('.js-test'); var className = $el.className;
querySelector only class
var $el = document.querySelector('div.js-test'); var className = $el.className;

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
querySelector with html tag
querySelector only class

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 3 years ago)

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 11_2_1) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/89.0.4389.82 Safari/537.36

Browser/OS: Chrome 89 on Mac OS X 11.2.1

View result in a separate tab

Test name	Executions per second
querySelector with html tag	2985468.8 Ops/sec
querySelector only class	2703864.0 Ops/sec

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

LLMs can make mistakes. Check important info.

Let's dive into the provided benchmark.

**What is tested:**

The benchmark compares two approaches to selecting an HTML element using JavaScript:

1. **`querySelector with html tag`**: This approach uses the `document.querySelector()` method to select an element by its HTML tag (in this case, `<div>`). The method returns a single element that matches the specified selector.
2. **`querySelector only class`**: This approach uses the same `document.querySelector()` method, but with a modified selector (`'div.js-test'`) that targets elements with the `class` attribute containing the value `'js-test'`. This approach is often referred to as "CSS selector" or "attribute-based selection".

**Options compared:**

The benchmark compares the performance of these two approaches:

* **HTML tag**: Using the HTML tag (e.g., `<div>`) to select an element.
* **Class attribute**: Using a class attribute (e.g., `class="js-test"` ) to select an element.

**Pros and Cons:**

**`querySelector with html tag`:**

Pros:

* Simple and straightforward approach.
* Easy to understand and implement.

Cons:

* May lead to slower performance, as the browser needs to check every HTML tag on the page to find a match.

**`querySelector only class`:**

Pros:

* Faster performance, as the browser can use a more efficient algorithm to find matching elements.
* More flexible than using HTML tags, as you can target elements with any CSS selector or attribute value.

Cons:

* Requires a good understanding of CSS selectors and attribute values.
* May be less readable for beginners.

**Other considerations:**

When choosing between these approaches, consider the following factors:

* **Readability**: If readability is important, using HTML tags might be a better choice, as it's more straightforward to understand what's happening in the code.
* **Performance**: If performance is critical, using class attributes with CSS selectors can provide faster execution times.
* **Maintainability**: If you need to support a wide range of element types or attribute values, using class attributes might be a better choice.

**Library and syntax:**

There are no specific libraries mentioned in the benchmark, but `document.querySelector()` is a built-in method provided by modern web browsers. It's also worth noting that some older browsers might not support this method, so you may need to use alternative approaches (e.g., `getElementById()` or `getElementsByClassName()`).

**Special JS feature:**

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

**Alternatives:**

If you're looking for other alternatives, consider the following:

* **`elementFromPoint()`**: A method provided by some older browsers (e.g., Internet Explorer) that allows you to get an element at a specific point on the page.
* **`getElementsByClassName()`**: A method that returns a list of elements with a specific class attribute value.
* **`querySelectorAll()`**: A method that returns a NodeList of all elements matching a specified CSS selector.

Keep in mind that each approach has its own trade-offs, and the best choice depends on your specific use case and requirements.

Related benchmarks:

querySelector with html tag vs querySelector only class (version: 0)

Comparing performance of: querySelector with html tag vs querySelector only class

Created: 3 years ago by: Guest

Jump to the latest result

querySelector with html tag

querySelector only class

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

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