Benchmark: concat vs spread by rulasfia

Tests:

Array.prototype.concat
let x = []; let y = []; for (let step = 0; step < 900; step++) { x.push(String(new Date().getTime()) + String(step)); if (step <= 200) y.push(String(Math.random()) + String(step)) } var z = x.concat(y);
spread operator
let x = []; let y = []; for (let step = 0; step < 900; step++) { x.push(String(new Date().getTime()) + String(step)); if (step <= 200) y.push(String(Math.random()) + String(step)) } var z = [ ...x, ...y ]

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

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/114.0.0.0 Safari/537.36 Edg/114.0.1823.58

Browser/OS: Chrome 114 on Windows

View result in a separate tab

Test name	Executions per second
Array.prototype.concat	1944.5 Ops/sec
spread operator	1924.8 Ops/sec

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

LLMs can make mistakes. Check important info.

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

**Benchmark Definition**

The benchmark is comparing two approaches to concatenate arrays in JavaScript:

1. `Array.prototype.concat()`
2. Spread operator (`[ ...x, ...y ]`)

The benchmark definition provides a script that generates two arrays, `x` and `y`, with 900 elements each. The first 200 elements of `y` are populated with random strings. The script then concatenates the two arrays using both approaches.

**What is being tested?**

The test is comparing the performance of two array concatenation methods:

1. `concat()`: This method creates a new array and copies the elements from both input arrays into it.
2. Spread operator (`[ ...x, ...y ]`): This method uses the spread operator to create a new array with all elements from both `x` and `y`.

**Options compared**

The two options are being compared in terms of execution speed.

**Pros and Cons**

Here's a brief overview of each approach:

1. **`Array.prototype.concat()`**
	* Pros:
		+ Well-established method
		+ Easy to understand and implement
	* Cons:
		+ Creates a new array, which can be memory-intensive for large arrays
		+ May have performance overhead due to the creation of a new array
2. **Spread operator (`[ ...x, ...y ]`)**
	* Pros:
		+ More concise and expressive than `concat()`
		+ Does not create a new array, which can be more memory-efficient for large arrays
	* Cons:
		+ May have performance overhead due to the creation of an array literal
		+ Less well-established method compared to `concat()`

**Library used**

None. This benchmark only uses built-in JavaScript features.

**Special JS feature or syntax**

The spread operator (`[ ...x, ...y ]`) is a new feature introduced in ES6. It's called the "rest/spread syntax" and allows you to expand arrays into a new array.

**Other considerations**

When choosing between `concat()` and the spread operator, consider the trade-offs between memory usage and performance. If you're working with large arrays, the spread operator may be more efficient in terms of memory usage. However, if you're working with small arrays or need to concatenate multiple arrays together, `concat()` might be a better choice.

**Alternatives**

If you want to explore other array concatenation methods, consider the following:

1. **Array.prototype.push()`: You can use `push()` to add elements to an existing array and then assign it back to itself.
2. **Array.prototype.splice()`: You can use `splice()` to remove elements from an array and then push new elements into it.

Keep in mind that these methods may have performance overhead or require more memory than `concat()` or the spread operator.

Related benchmarks:

concat vs spread by rulasfia (version: 0)

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

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

Created: one year 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 one month ago):