Benchmark: JS spread vs concat v123

Tests:

Spread
const list = [...Array(500).keys()] const newList = [...list, 500]
concat
const list = [...Array(500).keys()] const newList = list.concat(500)

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Spread
concat

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 25 days ago):

LLMs can make mistakes. Check important info.

Let's break down what's being tested in this benchmark.

**Benchmark Goal:**
The goal of this benchmark is to compare the performance of two ways to create a new array by concatenating an existing array with a single value: using the spread operator (`...`) and using the `concat()` method.

**Options Compared:**

1. **Spread Operator (`...`)**:
The spread operator is a modern JavaScript feature that allows you to expand an array into individual elements, creating a new array. In this benchmark, it's used to create a new array by spreading an existing array of numbers and then adding a single value (500) to the end.
2. **`concat()` Method**:
The `concat()` method is a built-in JavaScript function that concatenates one or more arrays into a new array. In this benchmark, it's used in the same way as the spread operator: creating a new array by concatenating an existing array of numbers with a single value (500).

**Pros and Cons:**

* **Spread Operator (`...`)**:
	+ Pros:
		- More concise and expressive syntax.
		- Often faster than `concat()` because it's optimized for performance.
	+ Cons:
		- Only supported in modern browsers and environments (ECMAScript 2015+).
		- May not work as expected in older browsers or environments.
* **`concat()` Method**:
	+ Pros:
		- Widely supported across browsers and environments.
		- Works in older browsers that don't support the spread operator.
	+ Cons:
		- Less concise and expressive syntax compared to the spread operator.
		- May be slower than the spread operator due to overhead.

**Other Considerations:**

* **Performance**: The benchmark results show that the spread operator is faster than `concat()` for this specific test case. This is because the spread operator is optimized for performance in modern browsers and environments.
* **Browser Support**: As mentioned earlier, the spread operator requires modern browsers that support ECMAScript 2015+. If you need to support older browsers, the `concat()` method may be a better choice.

**Library/Tool Used:**
There is no specific library or tool used in this benchmark. The test cases are simple JavaScript code snippets that demonstrate the performance of the spread operator and `concat()` method.

**Special JS Feature/Syntax:**
The spread operator (`...`) is a modern JavaScript feature introduced in ECMAScript 2015+. It's a concise way to create a new array by expanding an existing array or object into individual elements. This feature requires support for modern browsers and environments, but it provides a more expressive and efficient syntax compared to the `concat()` method.

**Alternatives:**
If you need to compare the performance of other ways to concatenate arrays, some alternatives could be:

* Using `Array.prototype.reduce()` to concatenate two arrays.
* Using `Array.prototype.push()` and `array.length` to concatenate two arrays.
* Using a library like Lodash or Ramda for array manipulation.

Keep in mind that these alternatives may have different performance characteristics and syntax requirements compared to the spread operator and `concat()` method.

Latest run results:

Run details: (Test run date: one year ago)

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/110.0.0.0 Safari/537.36

Browser/OS: Chrome 110 on Windows

View result in a separate tab

Test name	Executions per second
Spread	29653.1 Ops/sec
concat	22497.1 Ops/sec

Related benchmarks:

JS spread vs concat v123 (version: 0)

Comparing performance of: Spread vs concat

Created: one year ago by: Registered User

Jump to the latest result

Spread

concat

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 25 days ago):