Benchmark: Array.prototype.slice vs spread operator With slightly bigger array

Script Preparation code:

var params = Array(100).fill('Hello World');

Tests:

slice operator
var other = params.slice();
spread operator
var other = [ ...params ]

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
slice operator
spread operator

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/129.0.0.0 Safari/537.36

Browser/OS: Chrome 129 on Mac OS X 10.15.7

View result in a separate tab

Test name	Executions per second
slice operator	15912808.0 Ops/sec
spread operator	6572069.5 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 is being tested in the provided JSON benchmark.

**Benchmark Overview**

The benchmark compares two methods for creating a copy of an array: the traditional `slice()` method and the new ES6 spread operator (`[ ...params ]`).

**Options Being Compared**

There are two options being compared:

1. **Traditional `slice()` method**: This method creates a shallow copy of an array by specifying a start index, end index, and step value.
```javascript
var other = params.slice();
```
2. **ES6 spread operator (`[ ...params ]`)**: This method creates a new array by spreading the elements of the original array into a new array.

**Pros and Cons**

Here are some pros and cons of each approach:

1. **Traditional `slice()` method**
	* Pros:
		+ Can be faster for small arrays or arrays with few unique elements.
		+ More predictable and easier to understand.
	* Cons:
		+ Creates a shallow copy, which can lead to issues when dealing with objects that contain references.
		+ Less intuitive than the spread operator for large arrays.
2. **ES6 spread operator (`[ ...params ]`)**
	* Pros:
		+ Creates a new array and avoids modifying the original array.
		+ More concise and readable for large arrays.
		+ Can be faster for large arrays due to its optimized implementation.
	* Cons:
		+ May have performance issues when dealing with very large arrays (not tested in this benchmark).
		+ Less intuitive than `slice()` for small arrays or arrays with few unique elements.

**Library and Special JS Feature**

In this benchmark, the following library is used:

None. This benchmark does not use any external libraries.

No special JavaScript features are mentioned in the provided code snippets.

**Other Alternatives**

Some alternative approaches to creating an array copy include:

1. `Array.from()`: This method creates a new array from an array-like object or iterable.
```javascript
var other = Array.from(params);
```
2. Using `map()` and `concat()`: This approach creates a new array by mapping over the original array and concatenating the results.
```javascript
var other = params.map((x) => x).concat();
```
However, these approaches may have performance issues or be less intuitive than the spread operator.

**Benchmark Preparation Code**

The preparation code sets up an array of 100 elements, each containing the string "Hello World".
```javascript
var params = Array(100).fill('Hello World');
```
This creates a large array that can be efficiently copied using the spread operator.

Related benchmarks:

Array.prototype.slice vs spread operator With slightly bigger array (version: 0)

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

Comparing performance of: slice operator vs spread operator

Created: 5 years ago by: Guest

Jump to the latest result

slice operator

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):