Benchmark: Getting element index 2

HTML Preparation code:

<div id='list'></div>

Script Preparation code:

var list = document.getElementById('list');

for(i=0; i<1000; i++){
  const newEl = document.createElement('div');
  newEl.setAttribute('data-index', String(i));
  list.appendChild(newEl);
}

var items = list.children;
var item = items.item(500);

Tests:

indexOf
Array.prototype.indexOf.call(items, item);
data-index
item.getAttribute('data-index')

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
indexOf
data-index

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.

Let's dive into the explanation of the provided benchmark.

**Benchmark Definition**

The benchmark is designed to compare two approaches for retrieving an element index in JavaScript:

1. `Array.prototype.indexOf.call(items, item)`
2. `item.getAttribute('data-index')`

The first approach uses the `indexOf` method on the `items` array, which returns the index of the specified `item`. The second approach uses the `getAttribute` method to retrieve the value of the `data-index` attribute from the `item` element.

**Script Preparation Code**

The script preparation code is a loop that creates 1000 elements and appends them to an HTML list. Each element has a `data-index` attribute set to its index in the loop. The resulting list contains elements with indices ranging from 0 to 999.

**Html Preparation Code**

The HTML preparation code is simply a `<div>` element with an ID of "list".

**Individual Test Cases**

There are two test cases:

1. **indexOf**: This test case runs the `Array.prototype.indexOf.call(items, item)` approach.
2. **data-index**: This test case runs the `item.getAttribute('data-index')` approach.

**Pros and Cons of Each Approach**

**indexOf**:

Pros:

* Can be used with arrays of elements
* Can be faster for large datasets

Cons:

* May not work correctly if the array is modified while iterating
* Requires an explicit call to `call`, which can add overhead
* May not be suitable for non-array data structures (e.g., objects)

**data-index**:

Pros:

* Faster and more efficient for most use cases, especially with large datasets
* Does not require an explicit call to `call`
* Can be used with any element that has a `data-index` attribute

Cons:

* May not work correctly if the element's attribute is deleted or modified
* Requires the presence of a `data-index` attribute on each element

**Other Considerations**

* **Type coercion**: Both approaches assume that the `item` variable is an array-like object. If this assumption is not met, unexpected results may occur.
* **Null and undefined checks**: Neither approach checks for null or undefined values in the `items` or `item` variables.

**Libraries and Special JS Features**

In this benchmark, there are no libraries used, but it's worth noting that other libraries like Lodash or Ramda might be used to simplify or optimize the code.

There are no special JavaScript features used in this benchmark. However, if you're interested in exploring advanced JavaScript features, you can look into concepts like async/await, Promises, and Web Workers, which are not relevant to this specific benchmark.

**Alternatives**

If you'd like to explore alternative approaches or test different scenarios, here are some ideas:

* Compare the performance of using `Array.prototype.indexOf.call()` versus a simple loop.
* Test the impact of modifying the `items` array while iterating on the `indexOf` approach.
* Use a library like Lodash to simplify or optimize the code for both approaches.

Keep in mind that the best approach will depend on the specific requirements and constraints of your project.

Related benchmarks:

Getting element index 2 (version: 0)

indexOf vs getAttribute('data-index')

Comparing performance of: indexOf vs data-index

Created: 3 years ago by: Guest

Jump to the latest result

indexOf

data-index

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):