Benchmark: getElementById vs querySelector vs attribute

HTML Preparation code:

<div id="testElement" jsname="testElement"></div>

Tests:

getElementById
var el = document.getElementById('testElement'); var className = el.className;
querySelector
var el = document.querySelector('#testElement'); var className = el.className;
querySelector jsname
var el = document.querySelector('[jsname="testElement"]'); var className = el.className;

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
getElementById
querySelector
querySelector jsname

Fastest: N/A

Slowest: N/A

Latest run results:

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

LLMs can make mistakes. Check important info.

Let's break down the provided JSON and understand what is being tested in this JavaScript microbenchmark.

**Benchmark Definition**

The benchmark is designed to compare the performance of three different ways to retrieve an element from an HTML document:

1. `getElementById`
2. `querySelector`
3. `querySelector` with a custom attribute (`jsname`)

**Script Preparation Code and Html Preparation Code**

The script preparation code is empty, which means that no initialization or setup code is required for the benchmark.

The HTML preparation code includes a simple `<div>` element with an `id` attribute set to `"testElement"` and a `jsname` attribute set to `"testElement"`. This allows the benchmark to test the performance of each method on a single element.

**Individual Test Cases**

There are three individual test cases:

1. **getElementById**
This test case uses the `document.getElementById()` method to retrieve an element by its ID.
2. **querySelector**
This test case uses the `document.querySelector()` method with a simple selector (just the `#` symbol) to retrieve an element.
3. **querySelector jsname**
This test case uses the `document.querySelector()` method with a custom attribute (`jsname`) to retrieve an element.

**Library Usage**

None of the test cases use any external libraries.

**Special JS Features or Syntax**

The only special feature used in this benchmark is the `jsname` attribute, which is not a standard HTML attribute. However, it's likely that the browser being tested supports this custom attribute.

**Pros and Cons of Different Approaches**

Here are some general pros and cons of each approach:

* **getElementById**
	+ Pros: Simple and straightforward, widely supported.
	+ Cons: Can be slower than other methods if the element is not found immediately.
* **querySelector**
	+ Pros: More flexible and efficient than `getElementById`, can use multiple selectors.
	+ Cons: May require more processing power due to the complexity of the selector.
* **querySelector jsname**
	+ Pros: Custom attribute allows for more precise selection, potentially faster than other methods.
	+ Cons: Requires support for custom attributes, may not be widely supported.

**Other Alternatives**

Some alternative approaches that could have been used in this benchmark include:

* Using `getElementsByClassName()` instead of `querySelector`
* Using a CSS selector with `querySelectorAll()`
* Using a different library or framework to retrieve elements (e.g., jQuery)

However, the choice of `getElementById`, `querySelector`, and `querySelector jsname` likely aims to provide a simple and representative comparison of performance for these three methods.

Related benchmarks:

getElementById vs querySelector vs attribute (version: 0)

Comparing performance of: getElementById vs querySelector vs querySelector jsname

Created: 5 years ago by: Guest

Jump to the latest result

getElementById

querySelector

querySelector jsname

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

No previous run results

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