Benchmark: Arguments Copy Array

Script Preparation code:

function sliceCopy()
{
  return Array.prototype.slice.call(arguments, 0);
}

function dotsCopy()
{
  return [...arguments];
}

Tests:

Slice
sliceCopy("A","B","C","D","E","F")
Dots
dotsCopy("A","B","C","D","E","F")

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Slice
Dots

Fastest: N/A

Slowest: N/A

Latest run results:

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

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/605.1.15 (KHTML, like Gecko) Version/17.4.1 Safari/605.1.15

Browser/OS: Safari 17 on Mac OS X 10.15.7

View result in a separate tab

Test name	Executions per second
Slice	3477137.0 Ops/sec
Dots	8329414.0 Ops/sec

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

LLMs can make mistakes. Check important info.

Let's dive into the world of JavaScript microbenchmarks!

**Benchmark Definition JSON**

The provided JSON represents a benchmark named "Arguments Copy Array". This benchmark is designed to test how efficient JavaScript engines are when copying arrays using different methods.

**Script Preparation Code**

The script preparation code defines two functions: `sliceCopy` and `dotsCopy`. These functions take an arbitrary number of arguments and return a new array by either using the `Array.prototype.slice.call()` method or the spread operator (`...`) with the `arguments` object, respectively.

**Purpose of Library**

In this benchmark, we don't see any explicit library usage. However, it's worth noting that JavaScript engines are built on top of ECMAScript standards, which provide a set of libraries and APIs for various tasks, including array copying.

**Options Compared**

The two options being compared in this benchmark are:

1. **`Array.prototype.slice.call(arguments, 0)`**: This method uses the `slice()` function to create a new array with the specified elements, starting from index 0.
2. **`[...arguments]`**: This syntax uses the spread operator (`...`) to create a new array by iterating over the `arguments` object.

**Pros and Cons**

Here's a brief overview of each approach:

1. **`Array.prototype.slice.call(arguments, 0)`**:
	* Pros: More explicit control over the copying process.
	* Cons: May be slower due to the additional function call overhead.
2. **`[...arguments]`**:
	* Pros: Cleaner and more concise syntax.
	* Cons: May have performance implications due to the creation of a new array.

In general, `Array.prototype.slice.call(arguments, 0)` is considered a more verbose approach that can lead to slower execution times, while `[...arguments]` is often preferred for its brevity and readability.

**Special JS Features**

The benchmark doesn't use any special JavaScript features or syntax beyond what's standard in ECMAScript. No modern features like async/await, Promises, or generators are employed here.

**Other Alternatives**

For array copying, you might also consider using the following alternatives:

* `Array.from(arguments)` (ECMAScript 2015+): Similar to `[...arguments]`, but with a more explicit `from` argument.
* `new Array(arguments.length).fill().map((_, i) => arguments[i])` (ECMAScript 2015+): A more verbose approach that creates a new array with the same length as the original, and then maps each element from the `arguments` object.

However, these alternatives might not be as concise or efficient as the `[...arguments]` syntax.

**Benchmark Preparation Code**

The provided preparation code is quite simple and straightforward. It defines two functions that take an arbitrary number of arguments and return a new array using either the `slice()` method or the spread operator. This allows for easy comparison between different execution scenarios.

Overall, this benchmark provides a good starting point for measuring the performance differences between various JavaScript array copying methods, making it useful for identifying potential optimization opportunities in your own codebase.

Related benchmarks:

Arguments Copy Array (version: 0)

Comparing performance of: Slice vs Dots

Created: one year ago by: Guest

Jump to the latest result

Slice

Dots

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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