Benchmark: getElementById vs querySelectorAll

HTML Preparation code:

<div id="testElement" class="test" data-test="1"></div>

Tests:

getElementById
var el = document.getElementById('testElement'); var className = el.className;
querySelectorAll
var el = document.querySelectorAll('[data-a="1"]'); var className = el.className;

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
getElementById
querySelectorAll

Fastest: N/A

Slowest: N/A

Latest run results:

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

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_4) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/81.0.4044.138 Safari/537.36

Browser/OS: Chrome 81 on Mac OS X 10.15.4

View result in a separate tab

Test name	Executions per second
getElementById	4051480.8 Ops/sec
querySelectorAll	1089148.4 Ops/sec

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

LLMs can make mistakes. Check important info.

Let's break down the provided benchmark and explain what's being tested.

**Benchmark Definition**

The benchmark is defined in JSON format, which includes:

* `Name`: The name of the benchmark, which is "getElementById vs querySelectorAll".
* `Description`: An empty description field, indicating that this benchmark doesn't have a detailed description.
* `Script Preparation Code` and `Html Preparation Code`: These fields are empty, meaning no specific code needs to be run before the benchmark starts. However, the provided HTML structure (`<div id="testElement" class="test" data-test="1"></div>`) is used in both test cases.

**Individual Test Cases**

The benchmark consists of two test cases:

* `getElementById`: This test case measures the performance of using `document.getElementById` to retrieve an element with a specific ID.
* `querySelectorAll`: This test case measures the performance of using `document.querySelectorAll` to retrieve all elements that match a specific CSS selector.

**Libraries and Features**

In both test cases, no libraries are explicitly used. However, the `querySelectorAll` method uses the CSS selector syntax (`[data-a="1"]`), which is a standard feature in modern browsers. The `getElementById` method relies on the browser's built-in element lookup mechanism.

**Pros and Cons of Different Approaches**

There are two primary approaches being compared:

* **getElementById**: This approach uses the traditional, element-lookup-based method to retrieve an element by its ID.
	+ Pros: Well-established, widely supported, and relatively simple to implement.
	+ Cons: Can be slower than other methods for large datasets or complex queries.
* **querySelectorAll**: This approach uses a CSS selector to match elements based on their attributes, class names, or other properties.
	+ Pros: Can be faster than element-lookup-based methods for large datasets or complex queries. Also provides more flexibility in terms of query syntax.
	+ Cons: May require more expertise and setup time due to the complexity of CSS selectors.

**Browser Features**

The benchmark results show that Chrome 81 is used as the test browser, which means it has built-in support for both `getElementById` and `querySelectorAll`. The device platform and operating system are specified as Desktop (Mac OS X 10.15.4).

**Alternatives**

Other alternatives to these approaches include:

* **getElementsByClassName**: This method is similar to `querySelectorAll` but uses class names instead of attributes or CSS selectors.
* **getElementsByAttribute**: This method is similar to `getElementById` but allows searching by attributes, not just IDs.
* **querySelector** and `querySelectorAll` with a more specific syntax: These methods provide more advanced query capabilities, such as using multiple selectors or specifying more complex attribute values.

In summary, this benchmark compares the performance of two widely used JavaScript methods for element retrieval: `getElementById` and `querySelectorAll`. The results help identify which approach is faster in different browsers and scenarios.

Related benchmarks:

getElementById vs querySelectorAll (version: 0)

Comparing performance of: getElementById vs querySelectorAll

Created: 4 years ago by: Guest

Jump to the latest result

getElementById

querySelectorAll

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):