Benchmark: test123 - MeasureThat.net

HTML Preparation code:

<div id="div"></div>

Script Preparation code:

div.innerHTML = Array(10000).fill(0).map((el, i) => `<div id="id${i}" class="test${i}"></div>`)

Tests:

getElementById
Array(10000).fill(0).map((el, i) => document.getElementById(`id${i}`).className)
querySelector
Array(10000).fill(0).map((el, i) => document.querySelector(`#id${i}`).className)

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
getElementById
querySelector

Fastest: N/A

Slowest: N/A

Latest run results:

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

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/128.0.0.0 YaBrowser/24.10.0.0 Safari/537.36

Browser/OS: Yandex Browser 24 on Windows

View result in a separate tab

Test name	Executions per second
getElementById	152.2 Ops/sec
querySelector	0.7 Ops/sec

Autogenerated LLM Summary (model gpt-4o-mini, generated one month ago):

LLMs can make mistakes. Check important info.

The benchmark defined in the provided JSON tests two different methods for accessing HTML elements in the DOM (Document Object Model) using JavaScript: `getElementById` and `querySelector`. These methods are commonly used in web development, and the benchmark aims to compare their performance in terms of execution speed.

### Benchmarked Methods

1. **`getElementById`**:
   - **Description**: This method retrieves an element from the DOM using its unique `id`. It is one of the simplest and fastest ways to access a specific element because browsers optimize this function for efficiency. 
   - **Usage**: In the benchmark, it is used to get the `className` of 10,000 `<div>` elements created dynamically, each having a unique `id`.
   - **Pros**:
     - Fastest way to access an element by its `id`.
     - Direct and straightforward.
   - **Cons**:
     - Limited to selecting only one element (the first match with the specified id, since `id` must be unique within a document).
     - Cannot use complex selectors.

2. **`querySelector`**:
   - **Description**: This method allows selecting elements using CSS-like selectors. It can retrieve elements based on various attributes, such as class, id, or even complex combinations.
   - **Usage**: In the benchmark, it retrieves the same `className` from the same set of 10,000 `<div>` elements, selecting them via their unique `id` using a string interpolation approach.
   - **Pros**:
     - More flexible than `getElementById`, allowing for complex selections beyond just ids (e.g., selecting classes or attributes).
     - Can be useful when working with CSS selectors for layout or styles.
   - **Cons**:
     - Generally slower than `getElementById` due to the overhead of parsing the selector and searching through the DOM for matches.
     - May have additional performance penalties in cases with a very large number of elements in the document.

### Benchmark Results
From the benchmark results:
- The execution speed for `getElementById` is significantly faster (approximately 152.17 executions per second) compared to `querySelector` (approximately 0.73 executions per second). This stark difference highlights the performance optimization that browsers apply to `getElementById`.

### Other Considerations
- **Scalability**: While `getElementById` is optimal when you know you need to target a specific unique element, `querySelector` is powerful in managing dynamic UI changes where the same element might require different targeting strategies.
- **Usability**: For developers accustomed to CSS, `querySelector` provides a more intuitive and versatile approach, especially when working with multiple classes or attributes. However, for performance-critical situations where id-based access is sufficient, `getElementById` is preferable.
- **Browser Compatibility**: Both methods are widely supported across all modern browsers, but it's always good practice to verify performance across the target audience’s browser platforms.

### Alternatives
Other alternatives to accessing DOM elements include:
- **`getElementsByClassName`**: Useful for retrieving elements based on class names, but returns a live HTMLCollection (which can be less efficient and requires additional handling).
- **`getElementsByTagName`**: Similar functionality but retrieves elements based on their tag names, and also returns a live HTMLCollection.
- **`closest`** and **`parentElement`**: Used for traversing the DOM once an element is selected, providing a more structural manipulation of the DOM relative to the original selection.

Choosing the right method depends on the specific use case, balancing the need for performance with the flexibility required for effective DOM manipulation.

Related benchmarks:

test123 (version: 1)

Comparing performance of: getElementById vs querySelector

Created: one month ago by: Guest

Jump to the latest result

getElementById

querySelector

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model gpt-4o-mini, generated one month ago):