Benchmark: Array cloning 2023

Tests:

Slice
const arr = new Array(100000).fill(0).map(Math.random); arr.slice();
Spread
const arr = new Array(100000).fill(0).map(Math.random); [...arr];

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Slice
Spread

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/537.36 (KHTML, like Gecko) Chrome/116.0.0.0 Safari/537.36

Browser/OS: Chrome 116 on Mac OS X 10.15.7

View result in a separate tab

Test name	Executions per second
Slice	706.1 Ops/sec
Spread	249.5 Ops/sec

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

LLMs can make mistakes. Check important info.

Let's break down what's being tested in the provided benchmark.

**Benchmark Goal**

The benchmark aims to compare two different methods for cloning an array: using the `slice()` method and using the spread operator (`[...]`).

**Options Compared**

Two options are compared:

1. **Slice Method**: Using the `slice()` method to clone an array.
2. **Spread Operator**: Using the spread operator (`[...]`) to clone an array.

**Pros and Cons of Each Approach**

* **Slice Method**:
	+ Pros: Fast, efficient, and widely supported in older browsers.
	+ Cons: May not work as expected when dealing with complex data structures or when the input array is very large.
* **Spread Operator**:
	+ Pros: Modern, concise, and works well with modern JavaScript features. It's also more memory-efficient than `slice()`.
	+ Cons: Not supported in older browsers, and may be slower than `slice()` due to the overhead of creating a new array.

**Library**

There is no explicit library mentioned in the benchmark definition or test cases. However, it's likely that the JavaScript engine being tested (e.g., V8 in Chrome) implements these methods as part of its internal library.

**Special JS Feature/Syntax**

Neither of the tested approaches uses any special JavaScript features or syntax that would require additional explanation.

**Alternatives**

If you wanted to test alternative array cloning methods, some possible alternatives could include:

1. **Array.prototype.slice.call()**: This method creates a new array by calling `slice()` on an existing array.
2. **Array.from()**: This method creates a new array from an iterable (e.g., an array or a string).
3. **Array.prototype.reduce()**: This method can be used to clone an array by reducing it to a single value.

Keep in mind that these alternatives might not provide the same performance characteristics as `slice()` and the spread operator, depending on the specific use case and browser implementation.

Overall, this benchmark provides a simple yet informative comparison of two common array cloning methods in JavaScript, which can help identify performance differences between older and modern browsers.

Related benchmarks:

Array cloning 2023 (version: 0)

Comparing array cloning methods

Comparing performance of: Slice vs Spread

Created: one year ago by: Guest

Jump to the latest result

Slice

Spread

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

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