Benchmark: queryselector test small dom tree

HTML Preparation code:

<div class="parent" id="test"><div class="target"></div></div>

Tests:

Node.children + Array.from()
const parent = document.querySelector('.parent'); Array.from(parent.children).some(element => element.classList.contains('target'));
Node.children + Object.keys()
const parent = document.querySelector('.parent'); Object.keys(parent.children).some(key => parent.children[key].classList.contains('target'));
querySelector
const parent = document.querySelector('.parent'); !!parent.querySelector('.parent > .target');

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Node.children + Array.from()
Node.children + Object.keys()
querySelector

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: one year ago)

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/115.0.0.0 Safari/537.36 OPR/101.0.0.0

Browser/OS: Opera 101 on Mac OS X 10.15.7

View result in a separate tab

Test name	Executions per second
Node.children + Array.from()	809370.3 Ops/sec
Node.children + Object.keys()	872799.5 Ops/sec
querySelector	3478123.0 Ops/sec

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

LLMs can make mistakes. Check important info.

Let's break down the provided benchmark and explain what is being tested.

**Benchmark Definition**

The website `MeasureThat.net` provides a simple HTML structure for testing JavaScript performance:
```html
<div class="parent" id="test"><div class="target"></div></div>
```
This HTML represents a small DOM tree with two elements: a parent element (`<div class="parent">`) and a child element (`<div class="target">`).

**Individual Test Cases**

There are three test cases defined:

1. **Node.children + Array.from()**
```javascript
const parent = document.querySelector('.parent');
Array.from(parent.children).some(element => element.classList.contains('target'));
```
This test case uses the `Array.from()` method to create an array from the children of the parent element and then uses the `some()` method to check if any child element has a class named "target".

2. **Node.children + Object.keys()**
```javascript
const parent = document.querySelector('.parent');
Object.keys(parent.children).some(key => parent.children[key].classList.contains('target'));
```
This test case uses the `Object.keys()` method to get an array of keys (i.e., property names) from the children of the parent element and then uses the `some()` method to check if any child element has a class named "target".

3. **querySelector**
```javascript
const parent = document.querySelector('.parent');
!!parent.querySelector('.parent > .target');
```
This test case uses the `querySelector()` method with a CSS selector to select the child element with the class "target" within the parent element.

**Comparison of Options**

*   The three test cases use different approaches to access and manipulate the child elements:
    *   `Array.from()` creates an array from the children, allowing for more flexible iteration.
    *   `Object.keys()` provides a way to iterate over property names (keys) in the object (children).
    *   `querySelector()` uses a CSS selector to select the target element directly.

**Pros and Cons of Each Approach**

*   **Array.from()**: Pros:
    *   More flexible iteration over child elements.
    *   Can be faster for large DOM trees due to optimized array creation.
    Cons:
    *   May require more memory for creating an intermediate array.
*   **Object.keys():** Pros:
    *   Faster for small or medium-sized DOM trees since it avoids the overhead of array creation.
    Cons:
    *   Less flexible iteration over child elements compared to `Array.from()`.
*   **querySelector():** Pros:
    *   Fastest and most straightforward way to access a specific element by its class or ID.
    Cons:
    *   Limited flexibility due to the use of CSS selectors.

**Library Usage**

There is no explicit library usage in these test cases, but `Array.from()` uses the native `Array.prototype.from()` method, which is built-in to JavaScript. Similarly, `Object.keys()` and `querySelector()` are also part of the standard JavaScript API.

**Special JS Features/Syntax (Not applicable)**

Since this benchmark does not use any advanced JavaScript features or syntax beyond standard ES6 (ECMAScript 2015) functionality, there's no additional explanation needed for these cases.

**Alternatives**

Some possible alternatives to consider when writing similar benchmarks:

*   **Native methods**: Other native DOM methods like `forEach()`, `getElementsByClassName()` (for older browsers), or `getElementsByTagName()` can also be used.
*   **Library-specific APIs**: Depending on the specific use case, libraries like jQuery or React's DOM manipulation functions might be more suitable for accessing and manipulating elements.
*   **Custom solutions**: Writing custom JavaScript code to achieve a desired performance outcome could provide additional insights into execution paths.

Keep in mind that these alternatives may not necessarily affect the overall results but can influence the approach taken when writing similar benchmarks.

Related benchmarks:

queryselector test small dom tree (version: 0)

Comparing performance of: Node.children + Array.from() vs Node.children + Object.keys() vs querySelector

Created: one year ago by: Guest

Jump to the latest result

Node.children + Array.from()

Node.children + Object.keys()

querySelector

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

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