Benchmark: Compare spread operator and concat in arrays

Script Preparation code:

var array1 = [];
var array2 = [];

for (let i = 0; i < 1000; i++) {
  array1[i] = Math.floor(Math.random() * 100);
  array2[i] = Math.floor(Math.random() * 100);
}

Tests:

Using the spread operator
const array3 = [...array1, ...array2];
Using Array.prototype.concat
const array3 = array1.concat(array2);

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Using the spread operator
Using Array.prototype.concat

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 29 days ago):

LLMs can make mistakes. Check important info.

Let's break down what's being tested in this benchmark and analyze the options compared.

**Benchmark Description**
The benchmark is designed to compare the performance of two ways to concatenate arrays: using the spread operator (`...`) and `Array.prototype.concat()`.

**Options Compared**

1. **Using Spread Operator**: `const array3 = [...array1, ...array2];`
	* Pros:
		+ More concise and readable code.
		+ Can be faster for large arrays since it avoids creating an intermediate array.
	* Cons:
		+ Requires support for the spread operator in older browsers (pre-ES6).
		+ May have performance advantages in newer browsers with optimized spread operator implementation.
2. **Using Array.prototype.concat()**: `const array3 = array1.concat(array2);`
	* Pros:
		+ Wider browser support (works in all browsers that support JavaScript).
		+ Can be easier to understand for developers familiar with the `concat()` method.

**Performance Considerations**
The benchmark is designed to measure the execution time of each approach. In general, using the spread operator can lead to better performance for large arrays since it avoids creating an intermediate array. However, the actual performance difference may depend on various factors such as:

* Array size and distribution
* Browser support and optimization level
* JavaScript engine used (e.g., V8 in Chrome)
* CPU architecture

**Library Used**
The benchmark uses `Math.random()` to generate random numbers for populating the arrays.

**Special JS Feature or Syntax**
There is no specific use of special JavaScript features or syntax in this benchmark. Both approaches are relatively straightforward and don't rely on advanced ES6+ features like `let` or `const`.

**Alternatives**
Other alternatives to compare array concatenation methods could include:

* Using `Array.prototype.push()` with multiple arguments
* Using a library like Lodash's `concat` function
* Comparing the performance of custom implementations using different data structures (e.g., linked lists)

Keep in mind that these alternative approaches might not accurately represent real-world use cases and are intended to provide additional context for understanding the benchmark results.

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/107.0.0.0 Safari/537.36

Browser/OS: Chrome 107 on Mac OS X 10.15.7

View result in a separate tab

Test name	Executions per second
Using the spread operator	117915.7 Ops/sec
Using Array.prototype.concat	621934.0 Ops/sec

Related benchmarks:

Compare spread operator and concat in arrays (version: 5)

This benchmark is to compare the cost of using the spread operator

Comparing performance of: Using the spread operator vs Using Array.prototype.concat

Created: 5 years ago by: Registered User

Jump to the latest result

Using the spread operator

Using Array.prototype.concat

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 29 days ago):