Benchmark: Array.prototype.concat vs spread

Tests:

Array.prototype.concat
var params = [ "hello", true, 7 ]; var other = [ 1, 2 ].concat(params);
spread operator
var params = [ "hello", true, 7 ] var other = [ 1, 2, ...params ]

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 28 days ago):

LLMs can make mistakes. Check important info.

Let's break down the benchmark and explain what's being tested.

**Benchmark Overview**

The benchmark compares two approaches to concatenate arrays in JavaScript: the traditional `Array.prototype.concat()` method (also known as the "dot notation" approach) and the new ES6 spread operator (`...`). The test cases are designed to measure the performance difference between these two methods, specifically for concatenating small arrays.

**Test Case 1: Array.prototype.concat**

The first test case uses the traditional `concat()` method:
```javascript
var params = [ "hello", true, 7 ];
var other = [ 1, 2 ].concat(params);
```
This code creates two arrays, `[1, 2]` and `[hello, true, 7]`, and then concatenates them using the `concat()` method.

**Test Case 2: Spread Operator**

The second test case uses the new ES6 spread operator (`...`) to concatenate the same two arrays:
```javascript
var params = [ "hello", true, 7 ];
var other = [ 1, 2, ...params ];
```
This code creates two arrays, `[1, 2]` and `[hello, true, 7]`, and then uses the spread operator to concatenate them.

**Options Compared**

The benchmark compares the performance of two approaches:

1. **Traditional `Array.prototype.concat()` method**: This approach creates a new array by concatenating the elements of both input arrays using the `concat()` method.
2. **New ES6 spread operator (`...`)**: This approach uses the spread operator to concatenate the elements of both input arrays in a more concise way.

**Pros and Cons**

Here are some pros and cons of each approach:

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

Pros:

* Widely supported across browsers and Node.js versions
* Well-documented and understood by most developers

Cons:

* Creates a new array, which can lead to performance issues if the resulting array is very large.
* Less concise than the spread operator.

**New ES6 spread operator (`...`)**

Pros:

* More concise and expressive than traditional `concat()`.
* Can be faster for small arrays because it avoids creating an intermediate array.

Cons:

* Not as widely supported across browsers and Node.js versions (although improving).
* May not work well with older JavaScript engines or versions that don't understand the spread operator.

**Library Used**

In this benchmark, no external libraries are used. The tests only rely on built-in JavaScript features.

**Special JS Feature/Syntax**

The spread operator (`...`) is a new syntax introduced in ES6 (ECMAScript 2015). It allows for more concise way of concatenating arrays and spreading objects. While it's not the most widely supported feature yet, it's gaining popularity and becoming more widely adopted in modern JavaScript development.

**Alternative Approaches**

Other alternatives to concatenate arrays could include:

* Using `Array.prototype.push()` method to add elements one by one.
* Creating a new array using `Array.from()` method (although this would also create an intermediate array).
* Using a library like Lodash or Ramda for array manipulation, which often provide more concise and expressive methods for concatenating arrays.

Overall, the benchmark provides a good example of how to measure the performance difference between two approaches in JavaScript. By testing different methods, developers can gain insights into how their code might impact performance in different scenarios.

Latest run results:

Run details: (Test run date: 6 years ago)

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_14) AppleWebKit/605.1.15 (KHTML, like Gecko) Version/12.0 Safari/605.1.15

Browser/OS: Safari 12 on Mac OS X 10.14

View result in a separate tab

Test name	Executions per second
Array.prototype.concat	8365500.5 Ops/sec
spread operator	7915413.0 Ops/sec

Related benchmarks:

Array.prototype.concat vs spread (version: 0)

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

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 28 days ago):