Benchmark: JavaScript reverse vs toReversed

Script Preparation code:

array = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10];

Tests:

Array.reverse()
array.reverse();
Array.toReversed()
array.toReversed();

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Array.reverse()
Array.toReversed()

Fastest: N/A

Slowest: N/A

Latest run results:

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

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:149.0) Gecko/20100101 Firefox/149.0

Browser/OS: Firefox 149 on Mac OS X 10.15

View result in a separate tab

Test name	Executions per second
Array.reverse()	28036914.0 Ops/sec
Array.toReversed()	8826021.0 Ops/sec

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

LLMs can make mistakes. Check important info.

Let's break down the benchmark test and explain what's being tested.

**Benchmark Test:** Measuring the performance of `Array.reverse()` vs `Array.toReversed()`

The provided JSON represents a benchmark test that compares the performance of two different methods to reverse an array in JavaScript: `Array.reverse()` and `Array.toReversed()`.

**Options Compared:**

* `Array.reverse()`: This method reverses the order of elements in the array by swapping adjacent pairs of elements.
* `Array.toReversed()`: This method returns a new reversed copy of the array, without modifying the original array.

**Pros and Cons:**

* **`Array.reverse()`**: Pros:
	+ It's a built-in method in JavaScript, so it's likely to be implemented efficiently by the engine.
	+ It modifies the original array, which might be desirable in some cases.
* Cons:
	+ It reverses the entire array in place, which can lead to performance issues if the array is large or frequently updated.
	+ It doesn't create a new reversed copy of the array, so it affects the original data.
* **`Array.toReversed()`**: Pros:
	+ Creates a new reversed copy of the array, preserving the original data.
	+ Does not modify the original array, which can be beneficial in certain scenarios.
* Cons:
	+ It's a custom method implemented by the browser engine or test runner, so its performance might vary across different engines.
	+ It creates a new array object, which consumes more memory.

**Other Considerations:**

* The benchmark only measures the performance of these two specific methods. Other approaches to reverse an array, such as using `slice()` and `reverse()`, are not compared in this test.
* The benchmark assumes that the input arrays are large enough to demonstrate significant performance differences between the two methods.

**Library Usage:**

In the provided code snippets, there is no explicit library usage mentioned. However, it's worth noting that `Array.reverse()` and `Array.toReversed()` are built-in methods in JavaScript, so they don't rely on external libraries.

**Special JS Features or Syntax:**

There are no special JavaScript features or syntax used in this benchmark test. It only employs standard JavaScript methods and data structures.

**Alternatives:**

If you're interested in exploring alternative approaches to reverse an array, here are a few options:

* Using `slice()` and `reverse()`: This approach creates a new reversed copy of the array by slicing it from the beginning and reversing the slice.
```javascript
const arr = [1, 2, 3, 4, 5];
const reversedArr = arr.slice().reverse();
```
* Using `reduceRight()` with an initial value: This approach uses the `reduceRight()` method to iterate over the array from right to left and accumulate the elements in a new reversed array.
```javascript
const arr = [1, 2, 3, 4, 5];
const reversedArr = arr.reduceRight((acc, curr) => [...acc, curr], []);
```
Keep in mind that these alternatives might have different performance characteristics or memory implications compared to the built-in `Array.reverse()` and `Array.toReversed()` methods.

Related benchmarks:

JavaScript reverse vs toReversed (version: 2)

Compare Array.reverse() to Array.toReversed() performance wise.

Comparing performance of: Array.reverse() vs Array.toReversed()

Created: one year ago by: Registered User

Jump to the latest result

Array.reverse()

Array.toReversed()

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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