Let's break down what's being tested in this benchmark.

Benchmark Purpose

The purpose of this benchmark is to compare the performance of two different approaches to remove an element from an array:

1. FindIndex + splice: This approach uses the indexOf method to find the index of the target element, and then uses the splice method to remove it.
2. filter: This approach uses the filter method to create a new array with all elements that do not match the target element.

Comparison

The benchmark compares the execution times of these two approaches for an array of 150 elements. The tests are designed to be similar, so any differences in performance can be attributed to the specific implementation being compared.

Pros and Cons

• FindIndex + splice:
  • Pros: This approach is simple and easy to understand.
  • Cons: It requires multiple method calls, which can be slower than a single call for filtering. Additionally, splice modifies the original array, which may not be desirable in all cases.
• filter:
  • Pros: This approach is more concise and efficient, as it creates a new array with the desired elements in a single operation.
  • Cons: It requires creating a new array, which can be memory-intensive for large datasets.

Library/Functionality

• None of the benchmark code uses any external libraries or native JavaScript functions beyond what's included in the HTML5 specification. However, it does rely on:

ES6 Functionality

• FindIndex: This method is available in ECMAScript 2015 (ES6) and later versions. It returns the index of the first element that satisfies the provided callback function.
• filter: This method is also available in ES6 and later versions, allowing you to create a new array with elements that meet a certain condition.

Benchmark Preparation Code

The preparation code sets up an array arr with 150 elements, each containing only a unique identifier. The script then fills the array with values from 0 to 149 and maps over it to set the index of each element. Finally, it generates a random index foo between 0 and 149.

The test cases simply execute the provided benchmark definitions:

1. "FindIndex + splice" uses arr.indexOf(foo) followed by arr.splice(index, 1).
2. "filter" uses arr.filter(el => el !== foo), creating a new array with elements that do not match foo.

Alternatives

Other alternatives for removing an element from an array include:

• Using the map method to create a new array without modifying the original: arr.map((el, idx) => el.id === foo ? null : el)
• Using the forEach method to iterate over the elements and remove them individually.
• Using a custom solution with indexing or iteration.