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

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")
getElementsByTagName
document.getElementsByTagName('div');

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

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

Fastest: N/A

Slowest: N/A

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

LLMs can make mistakes. Check important info.

**Overview of the Benchmark**

MeasureThat.net provides a JavaScript microbenchmarking platform where users can compare the performance of different DOM query methods in JavaScript. The benchmark tests six query methods:

1. `document.querySelector()`
2. `document.querySelectorAll()`
3. `document.getElementsByClassName()`
4. `document.querySelector()` with an ID selector (`#test`)
5. `document.getElementById()` (Note: This is not a standard DOM method, it's likely a typo and should be `document.querySelector()` with an ID selector)
6. `document.getElementsByTagName('div')`

**Options Compared**

The benchmark compares the performance of each query method:

1. **`document.querySelector()`**: Selects the first element matching the specified selector.
2. **`document.querySelectorAll()`**: Returns a NodeList containing all elements matching the specified selector.
3. **`document.getElementsByClassName()`**: Returns a DOMCollection (a legacy API) containing all elements with the specified class name.
4. **`document.querySelector()` with ID selector**: Selects the element with the specified ID.
5. **`document.getElementById()`**: Not used in the benchmark, but could be an alternative to `document.querySelector()` with an ID selector.
6. **`document.getElementsByTagName('div')`**: Returns a DOMCollection containing all elements of type 'DIV'.

**Pros and Cons**

Here's a brief summary of each query method:

1. **`document.querySelector()`**: Fast and efficient, but only returns the first matching element. Pros: lightweight, fast. Cons: may not find all matching elements if there are multiple.
2. **`document.querySelectorAll()`**: Returns all matching elements, but may be slower than `querySelector()`. Pros: finds all matching elements. Cons: can be slower due to the need to process all matches.
3. **`document.getElementsByClassName()`**: Legacy API that's still supported for backward compatibility. Pros: widely supported, easy to use. Cons: deprecated, not as efficient as other methods.
4. **`document.querySelector()` with ID selector**: Fast and efficient when selecting an element by ID. Pros: lightweight, fast. Cons: only works if the element exists in the DOM.
5. **`document.getElementById()`**: Not used in the benchmark, but could be an alternative to `document.querySelector()` with an ID selector. Would likely have similar performance characteristics.

**Library and Special Features**

None of these query methods rely on specific libraries or features beyond the standard DOM API. However, it's worth noting that some browsers may have additional features or optimizations for certain query methods (e.g., Chrome's "querySelector" optimization).

**Other Alternatives**

In modern JavaScript development, you might consider using more efficient query methods like:

1. `document.querySelector()` with a CSS selector syntax (e.g., `.test`)
2. `document.querySelectorAll()` with a CSS selector syntax
3. Using modern APIs like `Element.contains()` or `Array.prototype.filter()`
4. Utilizing libraries like jQuery (although this would be overkill for a simple benchmark)

For most use cases, the standard DOM query methods are sufficient and efficient enough. However, if you're working on complex web applications with high-performance requirements, you may want to explore more advanced techniques or consider using a JavaScript framework or library that provides optimized query methods.

Latest run results:

Run details: (Test run date: 9 months ago)

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/121.0.0.0 Safari/537.36

Browser/OS: Chrome 121 on Windows

View result in a separate tab

Test name	Executions per second
querySelector	3834753.5 Ops/sec
querySelectorAll	1805169.2 Ops/sec
getElementsByClassName	4817523.5 Ops/sec
querySelector (ID)	2266917.8 Ops/sec
getElementsByID	4280555.0 Ops/sec
getElementsByTagName	5069459.0 Ops/sec

Related benchmarks:

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

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

Created: 9 months ago by: Registered User

Jump to the latest result

querySelector

querySelectorAll

getElementsByClassName

querySelector (ID)

getElementsByID

getElementsByTagName

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):