Benchmark: Array.prototype.concat vs spread operator - large arrays

Tests:

Array.prototype.concat
var list1 = []; var list2 = []; for(var i = 0; i<10000; i++) {list1.push(Math.random());list2.push(Math.random());} var result = list1.concat(list2);
spread operator
var list1 = []; var list2 = []; for(var i = 0; i<10000; i++) {list1.push(Math.random());list2.push(Math.random());} var other = [ ...list1, ...list2 ]

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

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

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

**Benchmark Definition**

The benchmark is designed to compare two approaches for concatenating arrays: the traditional `Array.prototype.concat()` method and the new ES6 spread operator (`...`).

**Options Compared**

Two options are compared:

1. **Traditional `Array.prototype.concat()`:** This method creates a new array by copying elements from one or more source arrays.
2. **Spread Operator (`...`):** This operator is used to create a new array by spreading the elements of an existing array.

**Pros and Cons**

* **Traditional `Array.prototype.concat()`:**
	+ Pros:
		- Well-established and widely supported method.
		- Easy to read and maintain code.
	+ Cons:
		- Creates a new array, which can lead to increased memory allocation.
		- May be slower due to the overhead of creating a new array.
* **Spread Operator (`...`):**
	+ Pros:
		- More concise and readable code.
		- Avoids the need for explicit array creation.
	+ Cons:
		- Less widely supported in older browsers or versions of JavaScript.
		- May lead to unexpected behavior if not used carefully.

**Library**

There is no specific library being tested in this benchmark. The focus is on comparing two native JavaScript methods.

**Special JS Feature/Syntax**

The spread operator (`...`) is a new feature introduced in ECMAScript 2015 (ES6). It allows for more concise and expressive code, but may require additional compiler or runtime support in older browsers or versions of JavaScript.

**Benchmark Preparation Code**

The provided script preparation code simply creates two empty arrays, `list1` and `list2`, and then populates them with random elements using a `for` loop. The benchmark then calls the `concat()` method on one array and uses the spread operator to concatenate the two arrays in another test case.

**Other Alternatives**

Before the spread operator was introduced, developers used other methods for concatenating arrays, such as:

* Using the `Array.prototype.push()` method repeatedly: `arr1.push(...arr2)`
* Creating a new array using the `Array.from()` method and passing an array literal with spread syntax: `[...arr1, ...arr2]`

However, these alternatives are not being tested in this benchmark.

I hope this explanation helps!

Related benchmarks:

Array.prototype.concat vs spread operator - large arrays (version: 0)

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

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

Created: 3 years ago by: Guest

Jump to the latest result

Array.prototype.concat

spread operator

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

No previous run results

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