Benchmark: Array.prototype.concat vs Spread operator

Tests:

Array.prototype.concat
const test = [].concat(Array(10000).fill('1')).concat(Array(100).fill('2'));
Spread operator
const test = [ ...Array(10000).fill('1'), ...Array(100).fill('2')];

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Array.prototype.concat
Spread operator

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 27 days ago):

LLMs can make mistakes. Check important info.

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

**Benchmark Definition**

The benchmark compares two approaches to concatenate arrays: the traditional `Array.prototype.concat()` method and the new ES6 spread operator (`...`).

**Options Compared**

Two options are compared:

1. **Traditional `Array.prototype.concat()`**: This method creates a new array by copying elements from two existing arrays.
2. **Spread Operator (`...`)**: This operator creates a new array by spreading the elements of an existing array.

**Pros and Cons**

Here's a brief summary of the pros and cons of each approach:

**Traditional `Array.prototype.concat()`**

Pros:

* Wide browser support (not just modern JavaScript engines)
* Can be used with older browsers that don't support the spread operator
* May be more familiar to developers who are used to this syntax

Cons:

* Creates a new array, which can lead to increased memory usage for large datasets
* Less efficient than the spread operator due to the need to iterate over each element in the original arrays

**Spread Operator (`...`)**

Pros:

* More concise and expressive syntax
* Efficient creation of a new array without the need for explicit iteration
* Supports modern JavaScript engines, including WebAssembly-based browsers

Cons:

* Requires support for the spread operator, which may not be available in older browsers or environments
* Can lead to unexpected behavior if not used carefully (e.g., with arrays containing non-iterable values)

**Other Considerations**

The benchmark assumes that the test case uses a large dataset (10000 elements) and is executed on a desktop platform. The spread operator may have performance advantages in this scenario due to its efficiency, but the actual results depend on various factors, such as browser implementation and system resources.

**Library Usage**

There is no explicit library usage mentioned in the provided data. However, it's worth noting that the benchmark might use libraries like `lodash` or other utility functions for array operations, which are not explicitly mentioned.

**Special JavaScript Features/Syntax**

The spread operator (`...`) is a modern JavaScript feature introduced in ECMAScript 2015 (ES6). It provides a concise way to create new arrays by spreading elements from an existing array. This syntax has become widely adopted in modern JavaScript development.

Overall, the benchmark aims to measure the performance difference between two approaches to concatenate arrays, with a focus on the spread operator's efficiency and traditional `Array.prototype.concat()` method's legacy support.

Latest run results:

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

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_14_6) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/79.0.3945.79 Safari/537.36

Browser/OS: Chrome 79 on Mac OS X 10.14.6

View result in a separate tab

Test name	Executions per second
Array.prototype.concat	28744.7 Ops/sec
Spread operator	21363.3 Ops/sec

Related benchmarks:

Array.prototype.concat vs Spread operator (version: 0)

Compare the new ES6 spread operator with the traditional concat() method on large datasets

Comparing performance of: Array.prototype.concat vs Spread operator

Created: 6 years ago by: Guest

Jump to the latest result

Array.prototype.concat

Spread operator

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 27 days ago):