Benchmark: Array merge (spread, concat)

Script Preparation code:

var arr = [].fill('', 0, 1024 * 1024);

Tests:

spread merge
const spread = [...[], ...arr];
concat
const concated = [].concat(arr);

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
spread merge
concat

Fastest: N/A

Slowest: N/A

Latest run results:

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

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

**Overview**

The benchmark is designed to measure the performance of two ways to merge an array in JavaScript: using `Array.prototype.concat()` (concat) and using the spread operator (`...`) (spread).

**Script Preparation Code**

The script preparation code initializes an array `arr` with 1024 kilobytes of empty values. This creates a large array that will be used for testing.

**Benchmark Definition JSON**

The benchmark definition JSON contains two test cases:

1. "Array merge (spread, concat)": This is the main test case that defines both the script preparation code and the test code.
2. Two individual test cases:
	* "concat": Defines the `concat` method as the primary operation to be measured.
	* "spread merge": Defines a custom function using the spread operator (`...`) to merge the array.

**Options Compared**

The benchmark compares two options:

1. **Concatenation**: Using the `Array.prototype.concat()` method to merge the arrays.
2. **Spread Operator**: Using the spread operator (`...`) to merge the arrays.

**Pros and Cons of Each Approach**

* **Concatenation**:
	+ Pros: Generally faster, especially for large arrays, since it uses a single function call and avoids creating intermediate arrays.
	+ Cons: Can be slower for smaller arrays or when using older browsers due to the overhead of the `concat()` method.
* **Spread Operator**:
	+ Pros: Often faster for small arrays, as it avoids the overhead of the `concat()` method. Also, more modern and widely adopted in JavaScript.
	+ Cons: Can be slower for large arrays, since it creates multiple intermediate arrays.

**Library**

There is no library used in this benchmark.

**Special JS Feature/Syntax**

There are two special features used:

1. **Spread Operator (`...`)**: A modern feature introduced in ECMAScript 2015 (ES6) that allows unpacking array elements into a new array.
2. `Array.prototype.concat()`: A method introduced in ECMAScript 2009 (ES5) that concatenates two or more arrays.

**Other Alternatives**

Other alternatives for merging arrays include:

* Using `Array.prototype.reduce()` and accumulating the results
* Using a custom loop to iterate over both arrays and merge them
* Using a library like Lodash, which provides a `merge` function for array merging

It's worth noting that the choice of approach (concatenation or spread operator) depends on the specific use case, performance requirements, and compatibility with different browsers and versions.

Related benchmarks:

Array merge (spread, concat) (version: 0)

Comparing performance of: spread merge vs concat

Created: 4 years ago by: Guest

Jump to the latest result

spread merge

concat

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):