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

getElementsByID

23.1M/s

getElementsByClassName

14.1M/s

querySelector

7.7M/s

querySelector (ID)

4.6M/s

querySelectorAll

2.1M/s

View exact numbers

Test name	Executions per second
✓ getElementsByID	23,114,458 Ops/sec
getElementsByClassName	14,138,496 Ops/sec
querySelector	7,697,261 Ops/sec
querySelector (ID)	4,570,806 Ops/sec
querySelectorAll	2,069,892 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.

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

Go 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):

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

Go 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):

Related benchmarks

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