Benchmark: Array.prototype.slice vs spread operator copy

Tests:

Array.prototype.slice
var params = [ "hello", true, 7 ]; var other = params.slice();
spread operator
var params = [ "hello", true, 7 ] var other = [ ...params ]

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Array.prototype.slice
spread operator

Fastest: N/A

Slowest: N/A

Latest run results:

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

User agent: Mozilla/5.0 (Linux; Android 10; K) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/120.0.0.0 Mobile Safari/537.36

Browser/OS: Chrome Mobile 120 on Android

View result in a separate tab

Test name	Executions per second
Array.prototype.slice	119386520.0 Ops/sec
spread operator	71111560.0 Ops/sec

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

LLMs can make mistakes. Check important info.

Let's dive into the explanation of the provided benchmark.

**What is being tested?**

The benchmark compares two approaches to create a copy of an array: the traditional `Array.prototype.slice()` method and the new ES6 spread operator (`[ ...params ]`). The test case creates an array `params` with three elements: a string, a boolean, and a number. It then measures the execution time for each approach to create a copy of this array.

**Options compared**

The benchmark is comparing two options:

1. **Array.prototype.slice()**: This method returns a shallow copy of the original array. It takes an optional start and end index as arguments.
2. **Spread operator (`[ ...params ]`)**: This operator creates a new array by spreading the elements of the original array into new positions.

**Pros and Cons**

1. `Array.prototype.slice()`:
	* Pros:
		+ Wide browser support (since 1998)
		+ Well-documented
	* Cons:
		+ Can be slow for large arrays due to the overhead of creating a new array object
2. Spread operator (`[ ...params ]`):
	* Pros:
		+ Fast and efficient, especially for large arrays
		+ Simple and concise syntax
	* Cons:
		+ Requires modern browsers that support ES6 (2009)
		+ May not be supported in older browsers

**Library usage**

In the benchmark, there is no explicit library usage. However, it's worth noting that the spread operator relies on the `Array.prototype.slice()` method internally to create a shallow copy of the array.

**Special JS feature or syntax**

The benchmark uses the ES6 spread operator (`[ ...params ]`), which was introduced in 2015 as part of the ECMAScript 2015 standard. This feature is supported by modern browsers and Node.js versions starting from ES6.

**Other alternatives**

If you need to support older browsers that don't support the spread operator, you can use alternative approaches:

1. **Array.prototype.slice()**: As mentioned earlier, this method is widely supported but may be slower for large arrays.
2. **Array.prototype.concat()**: This method creates a new array by concatenating multiple arrays or iterables. You can use `concat()` with an initial value to create a copy of the original array: `[ ...params ].concat()`.
3. **Array.from()**: If you're using modern browsers, you can use `Array.from()` with an iterable (in this case, the string `'hello'`) to create a new array: `Array.from(['hello'], String)`.

These alternatives may have different performance characteristics and are not as concise as the spread operator.

Related benchmarks:

Array.prototype.slice vs spread operator copy (version: 0)

Compare the new ES6 spread operator with the traditional slice() method

Comparing performance of: Array.prototype.slice vs spread operator

Created: 6 years ago by: Guest

Jump to the latest result

Array.prototype.slice

spread operator

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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