Benchmark: JavaScript array copy via spread op vs slice

Script Preparation code:

var arr = ['1','2','3','4','5','6','7','8']

Tests:

Copy via spread operator
[...arr]
Copy via slice
arr.slice()

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Copy via spread operator
Copy via slice

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 benchmark definition and test cases to understand what is being tested.

**Benchmark Definition:**

The provided JSON represents a JavaScript microbenchmark that compares two approaches to create a copy of an array:

1. Using the spread operator (`[...arr]`)
2. Using the `slice()` method (`arr.slice()`)

This benchmark aims to measure which approach is faster and more efficient in creating an array copy.

**Options Compared:**

Two options are compared:

a. **Copy via spread operator**: This method uses the spread operator (`[...]`) to create a new array by iterating over each element of the original array.
b. **Copy via slice**: This method uses the `slice()` method to create a shallow copy of the original array.

**Pros and Cons:**

1. **Copy via spread operator**:
	* Pros: Can be more concise and expressive in code, especially when dealing with complex data structures like objects or arrays.
	* Cons: May not be as efficient as other methods, especially for large datasets, since it involves creating a new array and iterating over each element.
2. **Copy via slice**:
	* Pros: Can be faster than the spread operator method, especially for large datasets, since it creates a shallow copy of the original array using a single function call.
	* Cons: May require more code to set up, as it involves calling the `slice()` method and handling edge cases like empty arrays.

**Library Usage:**

None of the test cases use any external libraries. The benchmark only relies on built-in JavaScript features.

**Special JS Features/Syntax:**

The test case uses the spread operator (`[...arr]`) which is a modern JavaScript feature introduced in ECMAScript 2015 (ES6). This syntax allows for creating new arrays from existing iterables, making it more concise and expressive. The `slice()` method is also a built-in JavaScript function.

**Other Alternatives:**

For array copying, other alternatives include:

* Using the `Array.prototype.copyWithin()` method (introduced in ECMAScript 2019)
* Using the `Array.from()` constructor with an iterable
* Using the `lodash` library's `cloneDeep()` function

However, these alternatives may not be as efficient or concise as the spread operator and slice methods used in this benchmark.

I hope this explanation helps software engineers understand what is being tested in the MeasureThat.net benchmark!

Related benchmarks:

JavaScript array copy via spread op vs slice (version: 0)

JavaScript array copy via spread operator vs slice

Comparing performance of: Copy via spread operator vs Copy via slice

Created: 3 years ago by: Guest

Jump to the latest result

Copy via spread operator

Copy via slice

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):