Benchmark: Array.prototype.slice vs Spread (2)

Tests:

Array.prototype.slice
var fooSet = []; for(var i=0;i<100;i++) { fooSet.push(i); } var other = fooSet.slice(0);
Spread
var fooSet = []; for(var i=0;i<100;i++) { fooSet.push(i); } var other = [...fooSet];

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Array.prototype.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/605.1.15 (KHTML, like Gecko) Version/18.5 Safari/605.1.15

Browser/OS: Safari 18 on Mac OS X 10.15.7

View result in a separate tab

Test name	Executions per second
Array.prototype.slice	2694673.0 Ops/sec
Spread	2532534.5 Ops/sec

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

LLMs can make mistakes. Check important info.

Let's break down what's being tested in this benchmark.

**Overview**
The test case is comparing two approaches to create a shallow copy of an array:

1. `Array.prototype.slice()`
2. The spread operator (`...`)

These two methods are often used interchangeably, but they have slightly different behavior and performance characteristics.

**Options Compared**

* **Array.prototype.slice()**: This method returns a new array object containing the elements from the original array, starting from the specified index (in this case, `0`). The returned array is a shallow copy of the original array.
* **Spread operator (`...`)**: This method creates a new array by spreading the elements of an iterable (like an array) into a new array.

**Pros and Cons**

* **Array.prototype.slice()**:
	+ Pros:
		- Widely supported and well-documented
		- Can be used to create a shallow copy of an array
	+ Cons:
		- Can be slower than the spread operator for large arrays, since it creates a new array object and copies the elements one by one.
* **Spread operator (`...`)**:
	+ Pros:
		- Faster than `Array.prototype.slice()` for large arrays, since it uses a more efficient copying mechanism
	+ Cons:
		- Requires support for modern JavaScript syntax (ES6+) and may not work in older browsers or environments.

**Library Used**
None in this case. The benchmark only uses built-in JavaScript features.

**Special JS Feature or Syntax**
The spread operator (`...`) is a new syntax introduced in ECMAScript 2015 (ES6+). It's used to create a new array by spreading the elements of an iterable into a new array.

**Other Alternatives**

* **Array.prototype.concat()**: This method returns a new array containing all elements from both arrays. While it can be used to create a shallow copy, it's not as efficient as the spread operator for large arrays.
* **Array.from()**: This method creates a new array from an iterable (like an array or string). It's not directly comparable to the spread operator in terms of performance.

In summary, this benchmark is testing the performance difference between two common ways to create a shallow copy of an array in JavaScript: `Array.prototype.slice()` and the spread operator (`...`). The results can help developers understand which approach to use depending on their specific use case and performance requirements.

Related benchmarks:

Array.prototype.slice vs Spread (2) (version: 0)

Comparing performance of: Array.prototype.slice vs Spread

Created: 7 years ago by: Guest

Jump to the latest result

Array.prototype.slice

Spread

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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