Benchmark: querySelector vs querySelector

HTML Preparation code:

<div id="foo" class="foo"></div>

Tests:

class
document.querySelector('.foo')
id
document.querySelector('#foo')

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
class
id

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 5 years ago)

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_14_4) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/80.0.3987.149 Safari/537.36

Browser/OS: Chrome 80 on Mac OS X 10.14.4

View result in a separate tab

Test name	Executions per second
class	829026.9 Ops/sec
id	478464.4 Ops/sec

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

LLMs can make mistakes. Check important info.

I'd be happy to explain the benchmark and its various components.

**What is tested:**
The provided JSON represents a microbenchmark test created on MeasureThat.net. The benchmark compares the performance of two approaches:

1. Using `document.querySelector` with a class selector (`'.foo'`)
2. Using `document.querySelector` with an ID selector (`'#foo'`)

In other words, the test measures how fast JavaScript can select elements from the DOM using both class and ID selectors.

**Options compared:**
Two options are being compared:

1. Class selector (`'.foo'`)
2. ID selector (`'#foo'`)

These two approaches differ in their syntax and semantics:

* Class selector: `.foo` matches all elements with the `class` attribute set to `"foo"`. This can match multiple elements, as a single element can have multiple classes.
* ID selector: `#foo` matches only one element with the `id` attribute set to `"foo"`.

**Pros and Cons of each approach:**

* **Class selector (`'.foo'`):**
	+ Pros:
		- Can match multiple elements, making it more flexible
		- May be faster for large datasets or when multiple elements need to be matched
	+ Cons:
		- May be slower due to the overhead of checking multiple classes on each element
* **ID selector (`'#foo'`):**
	+ Pros:
		- Typically faster and more efficient, as ID selectors are unique and directly accessable
	+ Cons:
		- Less flexible, as it can only match one specific element

**Library usage:**
In this benchmark, the `document.querySelector` method is being used. This method is part of the Document Object Model (DOM) API in JavaScript and provides a way to select elements from the DOM.

**Special JS feature/syntax:**
There is no special JavaScript feature or syntax mentioned in this benchmark.

**Other alternatives:**
If you need to compare performance of different DOM query methods, here are some alternative approaches:

* `document.querySelectorAll`: Similar to `querySelector`, but returns a NodeList with all matching elements.
* `getElementById` and `getElementsByTagName`: These methods provide access to individual elements or collections of elements by ID and tag name, respectively.

Keep in mind that the performance difference between these methods can vary depending on the specific use case, DOM structure, and browser version.

Related benchmarks:

querySelector vs querySelector (version: 0)

Comparing performance of: class vs id

Created: 5 years ago by: Guest

Jump to the latest result

class

id

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):