Benchmark: querySelector by attributte vs getElementById

HTML Preparation code:

<div id="testElement"><div id="testElement"></div><div id="testElement"></div><div id="testElement"></div><div id="testElement"></div><div id="testElement"></div><div id="testElement"></div><div id="testElement"></div><div id="testElement"></div><div id="testElement"></div><div id="testElement"></div><div id="testElement"></div><div id="testElement"></div><div id="testElement"></div><div id="testElement"></div><div id="testElement"></div><div id="testElement"></div><div id="testElement"></div><div id="testElement"></div><div id="testElement"></div><div id="testElement"></div><div id="testElement"></div><div id="testElement"></div><div id="testElement"></div><div id="testElement"></div><div id="testElement"></div><div id="testElement"></div><div id="testElement"></div><div id="testElement"></div><div id="testElement"></div><div id="testElement"></div><div id="testElement"></div><div id="testElement"></div><div id="testElement"></div><div id="testElement"></div><div id="testElement"></div><div id="trueElement" myattribute="trueElement"></div><div id="testElement"></div><div id="testElement"></div><div id="testElement"></div></div>

Tests:

getElementById
var el = document.getElementById('trueElement'); var className = el.className;
querySelector
var el = document.querySelector('[myattribute="trueElement"]'); var className = el.className;

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
getElementById
querySelector

Fastest: N/A

Slowest: N/A

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

LLMs can make mistakes. Check important info.

Let's dive into the benchmark and explain what's being tested.

**What is being tested?**

The provided JSON represents a JavaScript microbenchmark that compares two approaches for selecting HTML elements: `document.getElementById` versus `document.querySelector`.

**Options compared:**

Two options are being compared:

1. **`document.getElementById`**: This method retrieves an element by its ID.
2. **`document.querySelector`**: This method retrieves the first element that matches a given CSS selector.

**Pros and Cons of each approach:**

* **`document.getElementById`**:
	+ Pros:
		- Fast and efficient, as it directly accesses the DOM element by its unique identifier.
		- Can be faster when dealing with elements that have a unique ID.
	+ Cons:
		- May not work well for dynamic content or when there are multiple elements with the same ID (in which case, the last one in the HTML source order is returned).
* **`document.querySelector`**:
	+ Pros:
		- More flexible and powerful than `getElementById`, as it allows selecting elements based on various CSS selectors.
		- Can handle dynamic content and multiple elements with the same ID (in which case, it will return the first match in the selection order).
	+ Cons:
		- Generally slower than `getElementById` due to the overhead of parsing the CSS selector.

**Library usage:**

None of the provided benchmarks use any external libraries. They rely solely on the built-in JavaScript DOM APIs.

**Special JS features or syntax:**

The benchmark uses a simple CSS attribute selector (`[myattribute="trueElement"]`) in the `querySelector` test case. This is a valid CSS selector that matches elements with an attribute named "myattribute" and value "trueElement". The exact syntax might vary depending on the browser being tested.

**Alternative approaches:**

There are other methods for selecting HTML elements, such as:

* **`document.querySelectorAll`**: Retrieves multiple elements that match a given CSS selector.
* **`querySelectorAll` with a callback function**: Applies a callback function to each matched element.
* **`Element.prototype.querySelectorAll`**: A more concise way of selecting elements in some browsers (e.g., Edge).

However, these alternatives are not being compared in the provided benchmark.

Latest run results:

Run details: (Test run date: 4 years ago)

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:78.0) Gecko/20100101 Firefox/78.0

Browser/OS: Firefox 78 on Mac OS X 10.15

View result in a separate tab

Test name	Executions per second
getElementById	4371547.5 Ops/sec
querySelector	756972.8 Ops/sec

Related benchmarks:

querySelector by attributte vs getElementById (version: 0)

Comparing performance of: getElementById vs querySelector

Created: 4 years ago by: Guest

Jump to the latest result

getElementById

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):