Benchmark: slice vs destruction (obj)

Script Preparation code:

var list = [];
for (var i = 0; i < 1000 * 1000; i++) {
  list.push({ i });
}

Tests:

slice
const foo = list.slice()
destruction
const foo = [...list]

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
slice
destruction

Fastest: N/A

Slowest: N/A

Latest run results:

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

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/131.0.0.0 Safari/537.36

Browser/OS: Chrome 131 on Windows

View result in a separate tab

Test name	Executions per second
slice	1122.3 Ops/sec
destruction	1135.5 Ops/sec

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

LLMs can make mistakes. Check important info.

**Understanding the Benchmark**

The provided JSON represents a JavaScript microbenchmark test case on MeasureThat.net. The benchmark compares two approaches for copying an array: `Array.prototype.slice()` and the spread operator (`[...]`).

**Options Compared**

Two options are being compared:

1. **Slice Method**: This method creates a shallow copy of the original array by returning a new array object that references the same elements as the original array.
2. **Spread Operator**: This method creates a deep copy of the original array by creating a new array and copying all its elements into it.

**Pros and Cons**

Here's a brief overview of each approach:

* **Slice Method**
	+ Pros:
		- Lightweight, creating a new reference to the original array.
		- Fast, as it only requires an array copy operation.
	+ Cons:
		- Creates a shallow copy, which may not be suitable for all use cases (e.g., objects with nested arrays).
		- Can lead to unexpected behavior if the original array is modified after the slice method returns.
* **Spread Operator**
	+ Pros:
		- Creates a deep copy of the original array, preserving its structure and any nested arrays.
		- More predictable and safe than the slice method, as it can't be easily modified or manipulated accidentally.
	+ Cons:
		- Can be slower due to the overhead of creating a new array.
		- May require additional memory allocation.

**Library**

In this benchmark, none of the libraries are explicitly mentioned. However, it's likely that the `Array.prototype.slice()` method uses an internal implementation that may depend on browser-specific optimizations or internal library functions.

**Special JS Features**

The spread operator (`[...]`) is a modern JavaScript feature introduced in ECMAScript 2015 (ES6). It provides a concise way to create new arrays from existing ones, as well as from other iterable sources like strings, sets, and maps. This feature is widely supported across modern browsers.

**Other Alternatives**

If you're looking for alternative approaches to copying arrays, consider the following:

1. `Array.prototype.concat()`: Similar to the slice method, but creates a new array with all elements concatenated.
2. `Array.prototype.reduce()`: Can be used to create a new array by accumulating elements from the original array.
3. `Array.prototype.map()` or `Array.prototype.forEach()`: While not creating a new array directly, these methods can be used to transform or manipulate arrays.

Keep in mind that each approach has its own trade-offs and use cases. The choice of method ultimately depends on the specific requirements of your project.

Related benchmarks:

slice vs destruction (obj) (version: 0)

Comparing performance of: slice vs destruction

Created: 2 years ago by: Guest

Jump to the latest result

slice

destruction

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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