Benchmark: event delegation

HTML Preparation code:

<div id="container"><div class="one"></div>
<div class="many"></div><div class="many"></div><div class="many"></div><div class="many"></div>

Tests:

one
$('.one').on('click', function() {});
many
$('.many').on('click', function() {});
parent bound
$('#container').on('click', '.many', function() {});

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
one
many
parent bound

Fastest: N/A

Slowest: N/A

Latest run results:

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

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Let's break down the provided JSON to understand what's being tested.

**Benchmark Definition**

The benchmark is designed to measure the performance of event delegation in JavaScript. Event delegation is a technique used to optimize event handling by attaching an event listener to a parent element, which then propagates down to child elements that trigger the event.

In this case, the benchmark uses jQuery (as indicated by the `$` symbol) to attach event listeners to different elements:

1. `.one`: A single element with class `one`.
2. `.many`: Multiple elements with class `many`, repeated four times.
3. `#container > .many`: An element with id `container` and a child element with class `many`.

**Test Cases**

There are three test cases, each representing a different approach to event delegation:

1. **`.one`**: A single event listener is attached to the `.one` element. This represents the "bare-bones" case for event delegation.
2. **`.many`**: Multiple event listeners are attached to the `.many` elements. This represents a scenario with many elements that trigger the event.
3. **`#container > .many`**: An event listener is attached to the parent element (`#container`) and uses the delegated syntax (`.many`) to target child elements.

**Options Compared**

The benchmark compares three options:

* Using multiple event listeners on individual elements (`$.('.one').on('click', function() {})`, `$.('.many').on('click', function() {})`)
* Using a single event listener on a parent element and delegating down to child elements (`$('#container').on('click', '.many', function() {})`)

**Pros and Cons**

**Multiple Event Listeners (`.one` and `.many`):**

Pros:

* Easy to implement
* May be faster for simple scenarios

Cons:

* Can lead to unnecessary overhead and increased memory usage
* May not scale well with large numbers of elements

**Delegated Event Listeners (`#container > .many`):**

Pros:

* Scalable and efficient, even with many elements
* Reduces unnecessary event listeners and overhead

Cons:

* More complex implementation
* Requires careful handling of event propagation and capture/capture bubble behavior

**Library: jQuery**

jQuery is a popular JavaScript library that provides an easy-to-use API for DOM manipulation and event handling. In this benchmark, jQuery's `$` symbol is used to select elements and attach event listeners.

**Special JS Feature/ Syntax**

There is no special JavaScript feature or syntax being tested in this benchmark. However, the use of delegated event listeners does rely on the `event.target` property, which returns the element that triggered the event.

**Alternatives**

Some alternative approaches to event delegation include:

* Using a virtual DOM library like React or Angular
* Utilizing modern JavaScript features like `requestAnimationFrame` for optimized event handling
* Implementing custom event handling solutions using native JavaScript APIs

In general, event delegation is a widely used and effective technique for optimizing event handling in web applications. The choice of approach depends on the specific use case and performance requirements.

Related benchmarks:

event delegation (version: 0)

Comparing performance of: one vs many vs parent bound

Created: 8 years ago by: Guest

Jump to the latest result

one

many

parent bound

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):