Benchmark: Object arrays: findIndex vs forEach

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);
var result;

Tests:

findIndex
arr.findIndex((itm) => itm.id === foo);
forEach
arr.forEach((i, index) => { if (arr[i].id === foo) { result = 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 break down the provided benchmark and explain what's being tested.

**Benchmark Overview**

The benchmark compares two approaches to finding an element in an array:

1. `arr.findIndex((itm) => itm.id === foo)`
2. Using a traditional `for` loop with indexing (`arr.forEach`).

**Library Usage**

In this benchmark, the `Array.prototype.findIndex` method is used, which is a built-in JavaScript method introduced in ECMAScript 2015 (ES6). This method returns the index of the first element that satisfies the provided condition. In this case, it's used to find an object with a specific `id` value.

**Test Case Details**

The two test cases differ only in how they implement the search:

1. `findIndex`: Uses the `Array.prototype.findIndex` method directly.
2. `forEach`: Uses a traditional `for` loop with indexing to iterate through the array and check each element's `id` value.

**Comparison Options**

In this benchmark, we have two options being compared:

* **Using built-in methods (`arr.findIndex`)**: This approach uses a specialized method designed for finding elements in arrays. It's typically faster than traditional loops because it's implemented in native code.
* **Traditional loop (`forEach`) with indexing**: This approach uses a more generic `for` loop, which can be slower due to the overhead of the loop itself.

**Pros and Cons**

**Built-in methods (findIndex)**

Pros:

* Typically faster due to optimized native implementation
* More concise and expressive code
* Less prone to errors due to built-in type checking and null checks

Cons:

* Limited control over iteration order or element access
* May not work with custom data structures or non-array inputs

**Traditional loops (forEach)**

Pros:

* Provides more control over iteration order, indexing, and element access
* Can be used with a wider range of data structures (not just arrays)

Cons:

* Typically slower due to overhead of the loop itself
* More prone to errors due to manual indexing and conditionals

**Other Considerations**

In this benchmark, there are no special JS features or syntax being tested. However, in general, when considering performance-critical code, factors like:

* Cache locality: Built-in methods can exploit array caching, while traditional loops may not.
* Branch prediction: Traditional loops can be slower due to branch misprediction.
* Compiler optimizations: The browser's compiler may optimize built-in methods more efficiently.

**Alternatives**

If you need more control over iteration or performance-critical code, consider using:

* `for...of` loops (introduced in ECMAScript 2015) for iterative code
* `reduce()` method for more complex transformations
* Custom loop implementations with hand-tuned optimizations

Keep in mind that benchmarking results can vary depending on the specific use case and system.

Related benchmarks:

Object arrays: findIndex vs forEach (version: 0)

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

Comparing performance of: findIndex vs forEach

Created: 3 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):