Benchmark: Query Element - MeasureThat.net

HTML Preparation code:

<div class="myElement"></div>

Script Preparation code:

/*your preparation JavaScript code goes here
To execute async code during the script preparation, wrap it as function globalMeasureThatScriptPrepareFunction, example:*/
async function globalMeasureThatScriptPrepareFunction() {
    // This function is optional, feel free to remove it.
    // await someThing();
}

Tests:

Query Selector
document.querySelector(".myElement");
Get Element
document.getElementsByClassName("myElement");

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Query Selector
Get Element

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/108.0.0.0 Safari/537.36

Browser/OS: Chrome 108 on Windows

View result in a separate tab

Test name	Executions per second
RDFYjolf	1.0 Ops/sec
RDFYjolf	1.0 Ops/sec

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

LLMs can make mistakes. Check important info.

The benchmark defined in the provided JSON is focused on assessing the performance of two different methods for selecting DOM elements in a web page using JavaScript: `document.querySelector` and `document.getElementsByClassName`.

### Test Cases Explained

1. **Query Selector (`document.querySelector(".myElement")`)**:
   - This method allows the selection of an element based on a CSS selector. It returns the first element that matches the specified selector.
   - **Pros**:
     - Flexibility: Supports all CSS selectors (class, ID, attribute selectors, etc.).
     - Convenience: Cleaner syntax for complex queries.
   - **Cons**:
     - Performance: Generally slower than `getElementsByClassName` for simple class selections due to its versatility and complexity in parsing CSS selectors.

2. **Get Element (`document.getElementsByClassName("myElement")`)**:
   - This method directly fetches all elements that contain the specified class name. It returns a live HTMLCollection of elements.
   - **Pros**:
     - Simplicity: Faster for getting elements by class name as it does not require CSS parsing.
     - Efficiency: When only class name querying is required, it’s generally more efficient in terms of performance.
   - **Cons**:
     - Limitations: Cannot handle complex selectors. It only supports class names.

### Benchmark Results

- The results show the performance of each method measured in "ExecutionsPerSecond":
  - **Get Element**: 21,232,690 executions per second.
  - **Query Selector**: 17,816,952 executions per second.

The results indicate that `document.getElementsByClassName` performed better than `document.querySelector` in this particular benchmark, which aligns with the expected performance characteristics of these methods.

### Other Considerations

- **Selecting Elements**: In general application development, the choice between these methods depends on the specific use case. If the selection criteria are simple and well-defined (by class), `getElementsByClassName` is a better choice due to performance. If more complex selection is required, `querySelector` is more suitable despite being slightly slower.
  
- **Browser Compatibility**: Both methods are widely supported across modern browsers, though `getElementsByClassName` is older and thus has broader legacy support.

- **Return Types**: It's also essential to note that the return type differs. `querySelector` returns a single element (or null if none are found), while `getElementsByClassName` returns a live collection of elements, which can lead to unexpected results if changes to the DOM occur after the initial query.

### Alternatives

In addition to these two methods, other alternatives for element selection include:

- **`document.getElementById`**: This method returns a single element based on the ID attribute, which is the fastest method for selecting an element if its ID is known, but is limited to ID selectors.
- **`document.querySelectorAll`**: Similar to `querySelector`, but returns a static NodeList of all matching elements instead of just the first one.

In conclusion, when conducting performance benchmarks involving DOM manipulation, the choice of selection method can significantly impact your application's efficiency, making it critical to choose the appropriate method based on the context of use.

Related benchmarks:

Query Element (version: 1)

Comparing performance of: Query Selector vs Get Element

Created: one year ago by: Guest

Jump to the latest result

Query Selector

Get Element

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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