Benchmark: spread vs slice testt

HTML Preparation code:

const arr = ['hello', 1, { a: 'test' }];
const copy = arr.slice();

Script Preparation code:

const arr = ['hello', 1, { a: 'test' }];
const copy = [...arr];

Tests:

slice
const arr = ['hello', 1, { a: 'test' }]; const copy = arr.slice();
spread
const arr = ['hello', 1, { a: 'test' }]; const copy = [...arr];

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
slice
spread

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 4 years ago)

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 11_0_0) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/86.0.4240.198 Safari/537.36

Browser/OS: Chrome 86 on Mac OS X 11.0.0

View result in a separate tab

Test name	Executions per second
slice	44615976.0 Ops/sec
spread	33809524.0 Ops/sec

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

LLMs can make mistakes. Check important info.

Let's break down what's being tested in the provided benchmark.

The benchmark compares two ways of creating a copy of an array: using the spread operator (`[...arr]`) and using the `slice()` method.

**Spread Operator (`[...arr]`)**

The spread operator is a relatively recent feature introduced in ECMAScript 2015 (ES6). It allows you to expand an iterable (such as an array) into individual elements, which can then be used to create a new array. In the context of this benchmark, `const copy = [...arr];` creates a new array by spreading the original array's elements.

Pros:

* Creating a shallow copy of the array is relatively efficient and concise.
* The spread operator is often considered more readable than using a traditional loop to create a copy.

Cons:

* It can be slower for very large arrays, as it requires creating a new array object and copying all elements.
* Some older browsers may not support this feature, which could affect the benchmark's results.

**Slice Method (`arr.slice()`)**

The `slice()` method is a traditional way of creating a subset of an array. In this benchmark, `const copy = arr.slice();` creates a new array by taking a slice of the original array's elements.

Pros:

* The slice method is widely supported across most browsers and environments.
* It can be faster for very large arrays, as it uses optimized native code to create a new array object.

Cons:

* The syntax can be less readable than using the spread operator, especially for those unfamiliar with this method.
* Creating a shallow copy of the array may not work correctly if the original array contains nested objects or other complex data structures.

**Library: None**

Neither of these approaches relies on any external libraries. However, it's worth noting that some implementations of `slice()` might use additional libraries under the hood to optimize performance.

**Special JS Feature/Syntax: Spread Operator (`[...arr]`)**

The spread operator is a feature introduced in ECMAScript 2015 (ES6). It allows you to expand an iterable into individual elements, which can then be used to create a new array. This feature has become widely supported across modern browsers and environments.

Other alternatives:

* `Array.prototype.concat()`: This method creates a new array by concatenating the original array with other arrays or values.
* `Array.prototype.push()` followed by an assignment: This approach involves pushing all elements of the original array onto a new array, which can be less efficient than using either the spread operator or slice method.

Keep in mind that these alternatives may have different performance characteristics and use cases, depending on your specific requirements.

Related benchmarks:

spread vs slice testt (version: 0)

Comparing performance of: slice vs spread

Created: 4 years ago by: Guest

Jump to the latest result

slice

spread

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

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