Benchmark: Array.prototype.concat vs Spread operator

Tests:

Array.prototype.concat
const test = [].concatArray(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

Latest run results:

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

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/67.0.3396.99 Safari/537.36

Browser/OS: Chrome 67 on Windows

View result in a separate tab

Test name	Executions per second
Array.prototype.concat	0.0 Ops/sec
Spread operator	6987.5 Ops/sec

Autogenerated LLM Summary (model llama3.2:3b, generated 5 months ago):

LLMs can make mistakes. Check important info.

Let's dive into the world of JavaScript microbenchmarks on MeasureThat.net.

The provided benchmark measures the performance difference between two approaches for concatenating arrays in JavaScript: `Array.prototype.concat()` and the new ES6 spread operator (`...`).

**Options compared:**

1. **Array.prototype.concat()**: This method creates a new array by copying elements from two or more source arrays.
2. **Spread operator (`...`)**: This operator creates a new array by iterating over an iterable (such as an array) and creating a new element for each iteration.

**Pros and Cons of each approach:**

1. **Array.prototype.concat()**:
	* Pros:
		+ Widely supported in older browsers.
		+ Can be more predictable in terms of performance, since it creates a new array from scratch.
	* Cons:
		+ Requires an additional method call (`concat()`), which can add overhead.
		+ May perform poorly when dealing with very large arrays, as it needs to create a new array and copy all elements.
2. **Spread operator (`...`)**:
	* Pros:
		+ More concise and expressive than `Array.prototype.concat()`.
		+ Can take advantage of modern JavaScript optimizations, such as parallel execution of iterations.
	* Cons:
		+ May not be supported in older browsers or environments that don't understand the spread operator.
		+ Can lead to unexpected behavior if not used carefully (e.g., when concatenating arrays with different lengths).

**Library:**

None.

**Special JavaScript features or syntax:**

The benchmark uses ES6 spread syntax (`...`), which is a relatively new feature introduced in ECMAScript 2015. The spread operator allows you to create a new array by iterating over an iterable and creating a new element for each iteration.

**Other alternatives:**

1. **Array.prototype.push()**: Instead of concatenating two arrays, you could use `push()` to add elements to the end of one array.
2. **Array.prototype.reduce()**: You could use `reduce()` to concatenate two arrays by accumulating the results in an accumulator variable.
3. **String concatenation**: If you're only dealing with strings, you could concatenate them using the `+` operator or string literals.

Keep in mind that these alternatives may not be as efficient or concise as the spread operator or `Array.prototype.concat()`, depending on your specific use case and performance requirements.

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 5 months ago):