Let's break down the JavaScript microbenchmark on MeasureThat.net.

Benchmark Overview

The benchmark compares the performance of two methods: Array.prototype.findIndex and Array.prototype.indexOf. Both methods are used to find the index of a specific element in an array. The test creates a large array with 15,000 elements, each containing a unique identifier, and then randomly selects one element using the Math.random() function.

Options Compared

The two options being compared are:

1. Array.prototype.findIndex: This method returns the index of the first element in the array that satisfies the provided condition (in this case, the condition is num === foo). If no such element exists, it returns -1.
2. Array.prototype.indexOf: This method returns the index of the first occurrence of a specified value in the array.

Pros and Cons

• Array.prototype.findIndex has some advantages over Array.prototype.indexOf:
  • It is more flexible, as it allows for a callback function to be provided, which can be useful for more complex search conditions.
  • It returns -1 if no element satisfies the condition, whereas indexOf throws an error or returns -1.
• However, Array.prototype.indexOf has some advantages over findIndex:
  • It is generally faster and more efficient, especially for large arrays.
  • It does not require a callback function, making it easier to use.

Library and Purpose

The benchmark uses the JavaScript standard library's built-in methods: Array.prototype.findIndex and Array.prototype.indexOf.

Special JS Feature or Syntax

There are no special JS features or syntax used in this benchmark.

Other Considerations

When choosing between findIndex and indexOf, consider the following:

• If you need to perform a complex search condition, use findIndex.
• If you're searching for a specific value that may not exist in the array, be prepared to handle the case where it doesn't exist (using -1 or an error).
• If performance is critical and you're working with large arrays, consider using indexOf.

Alternatives

Other methods that could be used for finding the index of an element in an array include:

• Using a simple loop: for (var i = 0; i < arr.length; i++) { if (arr[i] === foo) { break; } }
• Using Array.prototype.includes: return arr.indexOf(foo) is equivalent to arr.includes(foo)
• Using a library like Lodash: _findIndex(arr, foo)

Keep in mind that these alternatives may have different performance characteristics and usage scenarios compared to findIndex and indexOf.