Benchmark: Comparing findIndex with map & indexOf

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
var index = arr.findIndex(el => el.id == foo);
map & indexOf
var index = arr.map(el => el.id).indexOf(foo)

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
findIndex
map & indexOf

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 2 years ago)

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/101.0.4951.54 Safari/537.36 Edg/101.0.1210.39

Browser/OS: Chrome 101 on Mac OS X 10.15.7

View result in a separate tab

Test name	Executions per second
findIndex	1467.1 Ops/sec
map & indexOf	13649.2 Ops/sec

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

LLMs can make mistakes. Check important info.

**Benchmark Explanation**

The provided JSON represents a JavaScript microbenchmark test case, where two different approaches are compared: using the `findIndex` method and using the `map` function in combination with the `indexOf` method.

**Approach 1: Using `findIndex`**

The first approach uses the `findIndex` method to find the index of an element in the array that matches a specific value (`foo`). The `findIndex` method returns the index of the first element in the array that satisfies the provided condition, or -1 if no element is found.

**Approach 2: Using `map` and `indexOf`**

The second approach uses the `map` function to create a new array with the `id` property of each element, and then uses the `indexOf` method to find the index of the value (`foo`) in the resulting array. This approach creates an intermediate array and searches for the value in that array.

**Comparison**

The main difference between these two approaches is how they handle the search operation:

* `findIndex`: Directly searches for the value in the original array, which may lead to better performance if the value is already present.
* `map` and `indexOf`: Creates an intermediate array with the transformed values, which can be slower due to the additional memory allocation.

**Pros and Cons**

* **FindIndex**: Pros:
	+ Faster search time since it only needs to scan the original array once.
	+ No unnecessary memory allocation.
Cons:
	+ May not work correctly if the value is not present in the array.
* **Map & IndexOf**: Pros:
	+ Can be more predictable and robust, especially when dealing with large datasets or complex conditions.
Cons:
	+ Requires additional memory allocation for the intermediate array.
	+ Slower search time due to the extra step of searching for the value.

**Library Used**

None explicitly mentioned in this benchmark. However, it's worth noting that JavaScript arrays use a few internal libraries and algorithms under the hood, but they are not typically exposed directly.

**Special JS Feature or Syntax**

This benchmark does not utilize any special JavaScript features or syntax beyond standard ECMAScript (ES) 2015+ features.

**Other Alternatives**

If you need to find an element in an array that matches a specific value, other approaches could include:

* Using the `includes` method: `arr.includes(foo)`
* Looping through the array manually using a traditional for loop
* Using a library like Lodash's `findIndex` or `indexOf`
* Using a different data structure, such as a Set, if you need fast lookups and the values are hashable.

Related benchmarks:

Comparing findIndex with map & indexOf (version: 0)

Comparing performance of: findIndex vs map & indexOf

Created: 2 years ago by: Registered User

Jump to the latest result

findIndex

map & indexOf

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

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