Benchmark: collect refs -> querySelector vs getElementsByClassName[0]

HTML Preparation code:

<todo-mvc>
    <header>
      <h1 class="headline1">Todo MVC</h1>
    </header>
    <todo-editor>
      <div class="input-wrapper">
        <input type="text" placeholder="What needs to be done?" class="input4">
        <div class="submitButton5">+</div>
      </div>
      <div tabindex="0" class="list6"></div>
      <div class="footer">
        <div class="count7">1 thing to do...</div>
        <undo-redo class="history8">
          <button class="undo9">Undo</button>
          <button class="redo10">Redo</button>
          <input type="range" min="0" class="timeline11">
        </undo-redo>
      </div>
  	</todo-editor>
    <footer>
      <p class="author2">Written by Anonymous</p>
      <p class="info3">No rights reserved.</p>
    </footer>
  </todo-mvc>

Script Preparation code:

var TodoMVC = document.querySelector('todo-mvc');
var classNames = [
  'headline1',
  'input4',
  'submitButton5',
  'list6',
  'count7',
  'history8',
  'undo9',
  'redo10',
  'timeline11',
  'author2',
  'info3'
];
var withDot = classNames.map(name => ('.' + name));

Tests:

querySelector
const collected = []; for (let i = 0; i < withDot.length; i++) { collected.push(TodoMVC.querySelector(withDot[i])); }
getElementsByClassName
const collected = []; for (let i = 0; i < classNames.length; i++) { collected.push(TodoMVC.getElementsByClassName(classNames[i])[0]); }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
querySelector
getElementsByClassName

Fastest: N/A

Slowest: N/A

Latest run results:

No previous run results

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

LLMs can make mistakes. Check important info.

Measuring performance differences between two approaches is crucial for optimizing code, and it's great that you're using MeasureThat.net to do just that.

**Benchmark Definition JSON**

The provided JSON defines two benchmark tests: `collect refs -> querySelector vs getElementsByClassName`. The script preparation code sets up a TodoMVC application with several elements, including some with classes that will be used in the benchmarks. The HTML preparation code generates the necessary HTML structure for the TodoMVC app.

**Benchmark Options**

The two benchmarks compare the performance of:

1. **querySelector**: A method to select an element by its CSS selector. It's a part of the DOM API and is generally considered more efficient than `getElementsByClassName`.
2. **getElementsByClassName**: A method that returns a live HTMLCollection of elements with a given class name.

**Pros and Cons**

* **querySelector**:
	+ Pros: Generally faster, more efficient, and more flexible (can select multiple elements using selectors).
	+ Cons: May not work as expected in older browsers or when dealing with CSS complexities.
* **getElementsByClassName**:
	+ Pros: Works in all modern browsers, including Internet Explorer, and can be used to select elements based on class names only.
	+ Cons: Can be slower due to the need to iterate over the entire collection.

**Library Usage**

The `TodoMVC` application is built using a JavaScript library that provides a simple implementation of the Model-View-Controller (MVC) pattern. It's likely a custom or third-party library, but its exact nature isn't specified in the provided information.

**Special JS Feature/Syntax**

None mentioned explicitly, but it's worth noting that MeasureThat.net uses some advanced features like `async/await` and modern JavaScript syntax to make benchmarking more efficient and accurate. However, these features aren't specific to the benchmarks themselves, but rather part of the overall testing framework.

**Other Alternatives**

If you need to compare performance differences between other approaches, you might consider using:

* **Element.fromQuerySelector**: A method introduced in modern browsers (e.g., Chrome 85+) that can improve performance for querySelector-heavy workloads.
* **CSS Selectors API**: Other methods like `querySelectorAll`, `querySelector`, and `getElementsByClassName` from the CSS Selectors API.

Keep in mind that these alternatives might not be as widely supported or optimized for your use case. MeasureThat.net's custom benchmarking framework provides a controlled environment to test specific scenarios, making it an excellent choice for comparing performance differences between different approaches.

Related benchmarks:

collect refs -> querySelector vs getElementsByClassName[0] (version: 0)

Comparing performance of: querySelector vs getElementsByClassName

Created: 4 years ago by: Guest

Jump to the latest result

querySelector

getElementsByClassName

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):