Benchmark: findIndex vs indexOf - JavaScript performance 2

Script Preparation code:

var arr = new Array(15000);

for (var i = 0; i < 15000; i++) {
	arr.fill({ id: i });
}

numArr = arr.map((el, idx) => el.id = idx);
var foo = Math.floor(Math.random() * 15000);

Tests:

findIndex
var index = arr.findIndex((obj) => obj.num === foo);
indexOf
var index = numArr.indexOf(foo);

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
findIndex
indexOf

Fastest: N/A

Slowest: N/A

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

LLMs can make mistakes. Check important info.

Let's break down the provided JSON and explain what's being tested, compared, and other considerations.

**What is being tested?**

The benchmark measures the performance of two JavaScript methods: `indexOf` and `findIndex`. These methods are used to find the index of a specific element within an array. The test creates a large array of 15,000 elements with a unique identifier (`id`) for each element, and then uses these arrays in both tests.

**Options compared**

The two options being compared are:

1. `indexOf`
2. `findIndex`

Both methods take two arguments: the array to search in and the value to search for. However, they differ in their approach:

* `indexOf` returns the index of the first occurrence of the specified value within the array.
* `findIndex` returns the index of the first occurrence of the specified value within the array, but it returns -1 if no element is found.

**Pros and Cons**

Here are some pros and cons for each approach:

* `indexOf`:
	+ Pros: Generally faster than `findIndex`, especially for small arrays.
	+ Cons: Returns the index of the first occurrence of the value, which may not be what the developer expects if there are duplicate values in the array.
* `findIndex`:
	+ Pros: Returns the actual element that matches the specified value, which can be more useful in some scenarios.
	+ Cons: Generally slower than `indexOf`, especially for small arrays.

**Library and purpose**

In this test case, the `map()` function is used to create a new array with the same elements as the original array, but with the indices assigned instead of the values. This creates two different arrays:

1. `arr`: The original array with unique identifiers (`id`) for each element.
2. `numArr`: A new array created by mapping the original array and assigning the indices to the values.

**Special JavaScript feature or syntax**

The `map()` function is a built-in JavaScript method that creates a new array with the results of applying a provided function on every element in this array. It's used here to create two different arrays, which are then used in both tests.

**Other alternatives**

There are other methods you could use to achieve similar results:

1. `Array.prototype.indexOf()`: This is an older method for finding the index of a value within an array.
2. `Array.prototype.findIndex()`: This is another method for finding the index of a value within an array, but it's generally slower than `indexOf`.
3. Using a loop to iterate through the array: You could use a simple loop to iterate through the array and find the index of the specified value.

However, in this test case, the focus is on comparing the performance of `indexOf` and `findIndex`, so using a different approach would likely change the results.

Latest run results:

Run details: (Test run date: one year ago)

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/112.0.0.0 Safari/537.36

Browser/OS: Chrome 112 on Mac OS X 10.15.7

View result in a separate tab

Test name	Executions per second
findIndex	747.1 Ops/sec
indexOf	635815.9 Ops/sec

Related benchmarks:

findIndex vs indexOf - JavaScript performance 2 (version: 0)

Comparing performance of: findIndex vs indexOf

Created: 4 years ago by: Registered User

Jump to the latest result

findIndex

indexOf

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

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