Benchmark: slice vs. spread operator

Tests:

spread
var a = [1, 2, 3, 4, 5, 6, 7, { a: 3 }]; var b = [...a];
slice
var a = [1, 2, 3, 4, 5, 6, 7, { a: 3 }]; var b = a.slice();

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
spread
slice

Fastest: N/A

Slowest: N/A

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

LLMs can make mistakes. Check important info.

Let's break down the benchmark and explain what is being tested.

**Benchmark Definition**

The benchmark measures the performance difference between two approaches: using the spread operator (`[...a]`) versus the `slice()` method to create a shallow copy of an array.

**Options Compared**

Two options are compared:

1. **Spread Operator**: The spread operator (`[...a]`) creates a new array by spreading the elements of the original array `a`. This approach is often used when creating a new array from an existing one, especially in modern JavaScript.
2. **Slice Method**: The `slice()` method returns a shallow copy of a portion of an array. In this case, it's used to create a new array by copying the entire original array `a`.

**Pros and Cons**

* **Spread Operator**:
	+ Pros: Modern, concise, and efficient for creating new arrays.
	+ Cons: May have performance overhead due to JavaScript engine optimizations, especially in older browsers or engines.
* **Slice Method**:
	+ Pros: Widely supported across different JavaScript engines and versions, potentially more efficient than spread operator in some cases.
	+ Cons: Can be verbose and less modern-looking syntax.

**Library and Purpose**

There is no library used in this benchmark. The benchmark focuses solely on the performance comparison between two built-in JavaScript features.

**Special JS Feature or Syntax**

The benchmark does not use any special JavaScript features or syntax that would require additional explanation.

**Other Alternatives**

If you're interested in exploring other array creation methods, here are a few alternatives:

* **Array.from()**: This method creates a new array from an iterable. It's often used when working with older browsers or engines that don't support the spread operator.
* **concat()**: This method concatenates two or more arrays and returns a new array. It's less efficient than the spread operator but can be useful in certain scenarios.

In conclusion, this benchmark provides a simple yet informative comparison of two common array creation methods in JavaScript: the spread operator and the `slice()` method. The results help users understand the performance implications of choosing one approach over the other in different scenarios.

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/99.0.4814.0 Safari/537.36 Edg/99.0.1135.5

Browser/OS: Chrome 99 on Mac OS X 10.15.7

View result in a separate tab

Test name	Executions per second
spread	1843337.8 Ops/sec
slice	31971838.0 Ops/sec

Related benchmarks:

slice vs. spread operator (version: 0)

Comparing performance of: spread vs slice

Created: 2 years ago by: Guest

Jump to the latest result

spread

slice

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):