Benchmark: Clone Array - 08/02/2024

Script Preparation code:

var arr1 = [1, 2, 3, , 5, 6, 7, 7, 8, 9, 10];

var arrCopy = null;

Tests:

Spread operator clone
arrCopy = [...arr1];
Slice
arrCopy = arr1.slice()

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Spread operator clone
Slice

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 2 years ago)

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/120.0.0.0 Safari/537.36

Browser/OS: Chrome 120 on Mac OS X 10.15.7

View result in a separate tab

Slice

7.0M/s

Spread operator clone

6.1M/s

View exact numbers

Test name	Executions per second
✓ Slice	7,008,384 Ops/sec
Spread operator clone	6,093,535 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 and explain what's being tested.

**Benchmark Overview**

The benchmark is designed to measure the performance of two approaches for cloning an array in JavaScript: using the spread operator (`[...]`) and using the `slice()` method. The test cases are identical, except that one uses the spread operator and the other uses the slice method.

**Options Compared**

Two options are being compared:

1. **Spread Operator Clone**: This approach creates a new array by spreading the elements of the original array into a new array. In this case, `var arrCopy = [...arr1];`.
2. **Slice Method**: This approach creates a shallow copy of the original array using the `slice()` method. In this case, `var arrCopy = arr1.slice();`.

**Pros and Cons**

Here are some pros and cons of each approach:

* **Spread Operator Clone**
	+ Pros:
		- Creates a deep copy of the array (i.e., all nested objects are copied recursively)
		- Can be faster for large arrays, since it only requires a single pass over the elements
	+ Cons:
		- May not work as expected with arrays containing non-primitive values (e.g., objects, functions, etc.)
* **Slice Method**
	+ Pros:
		- Works well with arrays containing non-primitive values
		- Can be more predictable and reliable than the spread operator approach
	+ Cons:
		- May require multiple passes over the array to create a deep copy, which can be slower for large arrays

**Library Used**

The benchmark uses the `null` value as a placeholder in the script preparation code. This suggests that the test case is not relying on any external libraries or frameworks.

**Special JavaScript Feature/Syntax**

There are no special JavaScript features or syntax being tested in this benchmark. The focus is solely on comparing two different approaches for cloning an array.

**Other Considerations**

When writing benchmarks like this, it's essential to consider factors such as:

* Array size: How large should the input array be? A small array may not accurately represent real-world performance.
* Data type: What types of data will be used in the benchmark? For example, if only primitive values are used, the spread operator approach may not work correctly.
* Browser and environment variations: As shown by the latest benchmark result, different browsers and environments can produce varying performance results.

**Other Alternatives**

Some alternative approaches for cloning an array include:

* Using `Array.prototype.map()` to create a new array with the same elements
* Using a library like Lodash or Underscore.js, which provide additional utility functions for working with arrays

However, these alternatives are not being tested in this specific benchmark.

Clone Array - 08/02/2024 (version: 0)

Comparing performance of: `Spread operator clone vs Slice`

Created: 2 years ago by: Guest

Go to the latest result

Spread operator clone

Slice

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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

Clone Array - 08/02/2024 (version: 0)

Comparing performance of: Spread operator clone vs Slice

Created: 2 years ago by: Guest

Go to the latest result

Spread operator clone

Slice

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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

Related benchmarks

Comparing performance of: `Spread operator clone vs Slice`