Benchmark: querySelector vs querySelectorAll vs getElementsByClassName vs querySelector (ID) vs getElementsByID Corrected

HTML Preparation code:

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

Tests:

querySelector
document.querySelector(".test")
querySelectorAll
document.querySelectorAll(".test")
getElementsByClassName
document.getElementsByClassName("test")
querySelector (ID)
document.querySelector("#test")
getElementsByID
document.getElementById("test")

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
querySelector
querySelectorAll
getElementsByClassName
querySelector (ID)
getElementsByID

Fastest: N/A

Slowest: N/A

Latest run results:

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

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/109.0.0.0 Safari/537.36

Browser/OS: Chrome 109 on Windows

View result in a separate tab

Test name	Executions per second
querySelector	7697261.0 Ops/sec
querySelectorAll	2069892.4 Ops/sec
getElementsByClassName	14138496.0 Ops/sec
querySelector (ID)	4570806.5 Ops/sec
getElementsByID	23114458.0 Ops/sec

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

LLMs can make mistakes. Check important info.

**Benchmark Overview**

The provided JSON represents a benchmarking test created on MeasureThat.net, which compares the performance of different JavaScript methods for selecting elements in an HTML document.

**Methods Being Tested**

1. `document.querySelector(".test")`: Uses the `querySelector` method with a CSS selector to select an element by its class.
2. `document.querySelectorAll(".test")`: Uses the `querySelectorAll` method with a CSS selector to select all elements that match the specified class.
3. `document.getElementsByClassName("test")`: Uses the `getElementsByClassName` method to retrieve a live HTMLCollection of elements whose class attribute contains the specified value.
4. `document.querySelector("#test")`: Uses the `querySelector` method with an ID selector to select an element by its ID.
5. `document.getElementById("test")`: Uses the `getElementById` method to retrieve the first element whose id attribute matches the specified value.

**Comparison of Methods**

The pros and cons of each method are:

1. **`document.querySelector(".test")`**: Fastest, but only selects one element. This is because `querySelector` returns a single result, which can lead to less work for the browser engine.
	* Pros: Fast, efficient
	* Cons: Only selects one element, may not be suitable for selecting multiple elements
2. **`document.querySelectorAll(".test")`**: Slower than `querySelector`, but returns all matching elements. This is because `querySelectorAll` returns a NodeList or HTMLCollection of all matched elements.
	* Pros: Returns all matching elements, can be used to select multiple elements at once
	* Cons: Slower, may require more work for the browser engine
3. **`document.getElementsByClassName("test")`**: Returns a live HTMLCollection of elements whose class attribute contains the specified value. This is because `getElementsByClassName` returns an array-like object that can be iterated over.
	* Pros: Returns all matching elements, can be used to select multiple elements at once
	* Cons: Slower than `querySelector`, may require more work for the browser engine due to the live collection nature
4. **`document.querySelector("#test")`**: Similar to `querySelector`, but uses an ID selector instead of a class selector.
	* Pros: Fast, efficient
	* Cons: Only selects one element, may not be suitable for selecting multiple elements
5. **`document.getElementById("test")`**: Returns the first element whose id attribute matches the specified value. This is because `getElementById` returns an HTML element or null if no match is found.
	* Pros: Fast, efficient
	* Cons: Only selects one element, may not be suitable for selecting multiple elements

**Library Used**

None of the methods require any additional libraries.

**Special JS Feature/ Syntax**

No special JavaScript features or syntax are used in these tests. The focus is on comparing the performance of different selection methods.

**Other Alternatives**

If you need to select elements in a more complex scenario, consider using:

1. `document.querySelectorAll("[data-test]")`: Uses an attribute selector to select elements based on their data- attributes.
2. `document.querySelector(":is(.test)")`: Uses a CSS pseudo-class to select elements that match a specific class or tag.

Keep in mind that the performance differences between these methods may vary depending on the specific use case and browser engine being used.

Related benchmarks:

querySelector vs querySelectorAll vs getElementsByClassName vs querySelector (ID) vs getElementsByID Corrected (version: 0)

Comparing performance of: querySelector vs querySelectorAll vs getElementsByClassName vs querySelector (ID) vs getElementsByID

Created: 2 years ago by: Guest

Jump to the latest result

querySelector

querySelectorAll

getElementsByClassName

querySelector (ID)

getElementsByID

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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