Benchmark: JS spread operator vs concat method

Script Preparation code:

var arr = [];
for (i = 0; i < 10; i++) {
    arr.push(i);
}

Tests:

coping array using spread operator
const result = [...arr, ...arr, ...arr]; return result;
coping array using concat method
const result = arr.concat(arr, arr); return result

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
coping array using spread operator
coping array using concat method

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 provided JSON and benchmark.

**Benchmark Definition**

The benchmark is designed to compare two methods for copying an array in JavaScript: the spread operator (`...`) and the `concat` method.

**Script Preparation Code**

The script preparation code creates an empty array `arr` with 10 elements, using a `for` loop. This ensures that both test cases will be comparing the performance of the copy operation on an identical input size.

**Html Preparation Code**

There is no HTML preparation code provided for this benchmark, which suggests that the focus is solely on JavaScript execution and does not involve any DOM-related operations.

**Individual Test Cases**

The benchmark consists of two individual test cases:

1. **Coping array using spread operator**
	* The benchmark definition uses the spread operator (`...`) to create a new copy of the `arr` array, repeating it three times.
2. **Coping array using concat method**
	* The benchmark definition uses the `concat` method to create a new copy of the `arr` array, followed by two calls to `concat` with the same argument.

**Library Usage**

There is no explicit library usage mentioned in the benchmark definition or test cases.

**Special JS Features/Syntax**

The use of the spread operator (`...`) and the `concat` method is a native JavaScript feature. The syntax for using the spread operator was introduced in ECMAScript 2015 (ES6).

**Pros and Cons of Each Approach**

1. **Spread Operator**
	* Pros:
		+ Can be more concise and expressive, especially when working with arrays.
		+ Often faster than `concat` due to its ability to create a new array without creating temporary elements.
	* Cons:
		+ May not be as familiar or intuitive for some developers, especially those from older JavaScript versions.
2. **Concat Method**
	* Pros:
		+ Widely supported and familiar in older JavaScript versions.
		+ Can be useful when working with mutable objects that require `concat` to maintain state.
	* Cons:
		+ Typically slower than the spread operator due to its need to create temporary elements.

**Other Alternatives**

In addition to the spread operator and the concat method, other methods for copying arrays in JavaScript include:

1. `Array.prototype.slice()`: Creates a shallow copy of an array using the slice method.
2. `Array.prototype.splice()`: Creates a new array by splicing the original array into multiple parts.

However, these alternatives are generally less efficient than the spread operator and concat method when used for simple array copying operations.

In summary, the benchmark is designed to compare the performance of two common methods for copying arrays in JavaScript: the spread operator and the `concat` method. The results should provide insight into which approach is faster and more suitable for this specific use case.

Related benchmarks:

JS spread operator vs concat method (version: 0)

Comparing performance of: coping array using spread operator vs coping array using concat method

Created: 5 years ago by: Registered User

Jump to the latest result

coping array using spread operator

coping array using concat method

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):