Benchmark: forEach vs findIndex

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
const index = arr.findIndex((itm) => itm.id === foo);
ForEach
const index = -1; arr.forEach((value, i) => { if (value.id === foo) { index = i } });

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
findIndex
ForEach

Fastest: N/A

Slowest: N/A

Latest run results:

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

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Let's dive into the benchmark.

The provided JSON represents a JavaScript microbenchmark that compares two approaches: using `findIndex` and using `forEach`. The test case creates an array of 15,000 elements, each with a unique `id` property. It then selects a random element from this array to search for.

**Library Used:**
In the benchmark preparation code, it uses the built-in JavaScript `Array.prototype.map()` function to populate the array with random IDs. This is a native JavaScript feature, not a library.

The `forEach` loop uses the same `map()` function under the hood, so both approaches are essentially using the same underlying data structure and operations.

**Options Compared:**
The two options being compared are:

1. **findIndex**: A method on the Array prototype that returns the index of the first element in the array that satisfies the provided testing function.
2. **forEach**: A method on the Array prototype that executes a user-supplied callback function once for each element in an array.

**Pros and Cons:**

* **findIndex**:
	+ Pros:
		- Returns the index directly, which can be more efficient for certain use cases.
		- Can be faster because it doesn't require iterating over the entire array to find a match (it stops as soon as it finds one).
	+ Cons:
		- If no element is found that matches the testing function, `findIndex` returns -1.
* **forEach**:
	+ Pros:
		- More intuitive and expressive than using an index-based approach.
		- Can be used with other array methods, like `map()` or `reduce()`.
	+ Cons:
		- Requires iterating over the entire array to find a match (or return -1 if no element is found).
		- May require additional steps to handle cases where no element is found.

**Other Considerations:**

* **Cache performance:** If you're working with large arrays and need to find an element multiple times, `findIndex` can be faster because it caches the search results.
* **Code readability and maintainability:** `forEach` may be more readable and maintainable for some developers because it makes it clear that each element is being processed.

**Special JavaScript Feature:**
The benchmark doesn't use any special JavaScript features like `let`, `const`, or arrow functions, which are relatively modern and not essential for understanding the basic comparison between `findIndex` and `forEach`.

**Alternatives:**

* Other methods to find an element in an array, such as using `filter()` followed by indexing into the resulting array (which is essentially what `forEach` does under the hood).
* Using a library like Lodash's `findIndex()` function, which provides a more robust and flexible way to search arrays.
* Implementing your own custom searching algorithm, like a binary search or a hash table-based lookup.

Related benchmarks:

forEach vs findIndex (version: 0)

Comparing performance of: findIndex vs ForEach

Created: 4 years ago by: Guest

Jump to the latest result

findIndex

ForEach

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

No previous run results

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