Benchmark: Step through array in reverse order - reduceRight vs reverse

Script Preparation code:

var nums50 = Array.from({length:  50}, () => Math.random() * 100 |0)
var nums150 = Array.from({length: 150}, () => Math.random() * 100 |0)
var nums500 = Array.from({length: 500}, () => Math.random() * 100 |0)

Tests:

slice and reverse 50
nums50.slice().reverse().forEach(n => n**2)
reduceRight 50
nums50.reduceRight((_,n) => n**2, null)
slice and reverse 150
nums150.slice().reverse().forEach(n => n**2)
reduceRight 150
nums150.reduceRight((_,n) => n**2, null)
slice and reverse 500
nums500.slice().reverse().forEach(n => n**2)
reduceRight 500
nums500.reduceRight((_,n) => n**2, null)

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
slice and reverse 50
reduceRight 50
slice and reverse 150
reduceRight 150
slice and reverse 500
reduceRight 500

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 6 months ago)

User agent: Mozilla/5.0 (Windows NT 10.0; rv:109.0) Gecko/20100101 Firefox/115.0

Browser/OS: Firefox 115 on Windows

View result in a separate tab

Test name	Executions per second
slice and reverse 50	3833368.8 Ops/sec
reduceRight 50	6111105.0 Ops/sec
slice and reverse 150	669208.7 Ops/sec
reduceRight 150	924154.1 Ops/sec
slice and reverse 500	222402.5 Ops/sec
reduceRight 500	260928.6 Ops/sec

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

LLMs can make mistakes. Check important info.

**Benchmark Overview**

The provided benchmark, hosted on MeasureThat.net, aims to measure the performance differences between two approaches for reversing an array in JavaScript: using `reverse()` with `forEach` or `reduceRight()`. The benchmark is designed to test the execution speed of these methods on arrays of varying sizes (50, 150, and 500 elements).

**Approaches Compared**

There are two main approaches being compared:

1. **`slice().reverse().forEach(n => n**2)`**: This approach creates a new array by reversing the original array using `reverse()`, and then iterates over the reversed array using `forEach()` to square each element.
2. **`nums.reduceRight((_,n) => n**2, null)`**: This approach uses the `reduceRight()` method to iterate over the array from right to left, squaring each element as it goes.

**Pros and Cons of Each Approach**

1. **`slice().reverse().forEach(n => n**2)`**:
	* Pros: Easy to understand, intuitive syntax.
	* Cons: Creates a new array, which can be memory-intensive for large datasets. Iteration using `forEach()` may not be the most efficient approach.
2. **`nums.reduceRight((_,n) => n**2, null)`**:
	* Pros: Efficient use of array iteration, reduces memory allocation compared to creating a new array.
	* Cons: Requires knowledge of `reduceRight()` and its usage, which may be unfamiliar to some developers.

**Library/ Framework Considerations**

There is no specific library or framework mentioned in the benchmark definition. However, it's worth noting that the use of `Array.prototype.forEach()` implies a reliance on modern JavaScript features, assuming the target browser supports it (e.g., Firefox 115).

**Special JS Features/Syntax**

The benchmark uses a few special JavaScript features:

* **Arrow functions**: Used for concise function definitions in both approaches.
* **Template literals**: Used to create string expressions with embedded values (`n**2`).
* **`reduceRight()` method**: A specialized array iteration method that reduces the array from right to left.

These features are supported by most modern JavaScript engines, including those used by MeasureThat.net.

**Other Alternatives**

If you're looking for alternative approaches or optimizations:

1. **Use `Array.prototype.map()` and `Array.prototype.reduce()`**: Instead of creating a new array using `reverse()`, consider using `map()` to square each element directly in the original array, followed by reducing the resulting array.
2. **Avoid unnecessary iterations**: Consider optimizing the iteration process by only iterating over the relevant elements or using more efficient algorithms (e.g., bit manipulation).

However, these alternatives may not be as straightforward to implement and might require additional code complexity.

Keep in mind that the performance differences between these approaches will depend on the specific JavaScript engine, browser, and system configuration. MeasureThat.net provides valuable insights into the relative performance of different techniques, allowing developers to make informed decisions about their coding choices.

Related benchmarks:

Step through array in reverse order - reduceRight vs reverse (version: 0)

Comparing performance of: slice and reverse 50 vs reduceRight 50 vs slice and reverse 150 vs reduceRight 150 vs slice and reverse 500 vs reduceRight 500

Created: one year ago by: Guest

Jump to the latest result

slice and reverse 50

reduceRight 50

slice and reverse 150

reduceRight 150

slice and reverse 500

reduceRight 500

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):