Benchmark: Object arrays: findIndex vs for loop (length cached)

Script Preparation code:

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

Tests:

findIndex
arr.findIndex((itm) => itm.id === foo);
for loop
const length = arr.length; for (let i = 0; i < length; i++) { if (arr[i].id === foo) break; }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
findIndex
for loop

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 benchmark and its options.

**Benchmark Overview**

The provided JSON represents a JavaScript microbenchmark test case on MeasureThat.net. The test aims to compare two different approaches for finding an element in an array: using the `Array.prototype.findIndex()` method or a traditional `for` loop.

**Options Being Compared**

The two options being compared are:

1. **findIndex()**: This is a built-in JavaScript method that returns the index of the first element in the array that satisfies the provided condition (in this case, `foo === itm.id`). If no such element exists, it returns `-1`.
2. **Traditional For Loop**: This approach uses a `for` loop to iterate through the elements of the array and checks each element's `id` property until it finds a match.

**Pros and Cons of Each Approach**

**findIndex():**

Pros:

* More concise and expressive code
* Reduced chance of off-by-one errors (since the index is returned directly)
* Built-in method, so no additional library or setup required

Cons:

* May be slower due to the need to iterate over the array's internal elements to find the correct position for `foo`
* Can be affected by JavaScript engine optimizations and cache behavior

**Traditional For Loop:**

Pros:

* More control over the iteration process (no risk of off-by-one errors)
* Less dependence on built-in method implementations
* May be faster in certain scenarios due to optimized loop execution

Cons:

* More verbose code, which can lead to increased cognitive load and decreased readability
* Requires manual indexing and array bounds checking

**Library and Syntax Considerations**

In this benchmark, the `Array.prototype.findIndex()` method is used, which is a part of the standard JavaScript library. There are no custom libraries or special syntax features involved.

**Other Alternatives**

Some other approaches for finding an element in an array include:

* Using `Array.prototype.indexOf()`, which returns the index of the first occurrence (instead of `-1` if not found)
* Using `Array.prototype.reduce()` and `Math.min()` to find the smallest index
* Using a more advanced algorithm, such as binary search

However, these alternatives are likely to be slower or less efficient than the `findIndex()` method and traditional for loop approaches.

**Benchmark Preparation Code**

The preparation code provided creates an array of 15,000 objects with unique `id` properties using the `Array.prototype.fill()` and `Array.prototype.map()` methods. It then sets a random value for `foo` to test in the search.

**Test Cases**

The benchmark consists of two individual test cases:

* **findIndex()**: Tests the `Array.prototype.findIndex()` method with the provided condition (`foo === itm.id`)
* **for loop**: Tests the traditional `for` loop approach using an index variable and array bounds checking

These test cases are likely executed multiple times to generate a set of execution results, which is then displayed on MeasureThat.net.

Latest run results:

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

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/116.0.0.0 Safari/537.36

Browser/OS: Chrome 116 on Windows

View result in a separate tab

Test name	Executions per second
findIndex	1326.8 Ops/sec
for loop	714.4 Ops/sec

Related benchmarks:

Object arrays: findIndex vs for loop (length cached) (version: 0)

Testing finding an object array via findIndex or by using a for loop

Comparing performance of: findIndex vs for loop

Created: one year ago by: Guest

Jump to the latest result

findIndex

for loop

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):