Benchmark: Array.prototype.concat vs spread operator better

Tests:

Array.prototype.concat
var array1 = [ 1, 2 ]; var array2 = [ "hello", true, 7 ]; var array3 = array1.concat(array2);
spread operator
var array1 = [ 1, 2 ]; var array2 = [ "hello", true, 7 ]; var array3 = [ ...array1, ...array2 ]

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Test case name	Result
Array.prototype.concat
spread operator

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

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**Benchmark Purpose and Comparison**

The benchmark tests two approaches to concatenate arrays: `Array.prototype.concat()` and the new ES6 spread operator (`...`).

The purpose of this benchmark is to compare the performance of these two methods, which are commonly used in JavaScript for merging arrays. The comparison aims to determine which method is more efficient.

**Options Compared**

Two options are compared:

1. **Array.prototype.concat()**: This method creates a new array and copies all elements from both input arrays into it.
2. **Spread Operator (`...`)**: This method creates a new array by spreading the elements of an existing array (or arrays) into a new array.

**Pros and Cons**

Here are some pros and cons of each approach:

* `Array.prototype.concat()`:
	+ Pros:
		- Widely supported across browsers and JavaScript versions.
		- Easy to read and understand for developers familiar with the method.
	+ Cons:
		- Creates a new array, which can lead to performance issues with large datasets.
		- Can be slower due to the creation of a new object.
* Spread Operator (`...`):
	+ Pros:
		- More concise and readable than `concat()`.
		- Does not create a new array, as it modifies the existing one in place.
	+ Cons:
		- May not be supported across older browsers or JavaScript versions (although most modern ones support it).
		- Can be slower due to the complexity of the spread operation.

**Library and Special JS Features**

Neither of these options uses a library, but they do rely on some special JavaScript features:

* `Array.prototype.concat()` relies on the `concat()` method and array concatenation syntax.
* Spread Operator (`...`) relies on the spread operator syntax and array destructuring.

**Other Considerations**

When evaluating performance, consider factors such as:

* Array size: Larger arrays may exhibit different behavior between the two methods.
* Browser and JavaScript version support: Ensure that both methods are supported across a wide range of browsers and JavaScript versions.
* Performance-critical code: In high-performance applications, using `...` might be beneficial due to its in-place nature.

**Alternatives**

If you need alternative approaches for concatenating arrays, consider the following:

1. `Array.prototype.reduce()`: Instead of concatenation, use `reduce()` to accumulate elements into a new array.
2. `Array.prototype.map()` and `Array.prototype.concat()`: Use `map()` to transform elements and then concatenate using `concat()`.
3. Other libraries or frameworks: Depending on your specific requirements, you might consider using a library like Lodash or Underscore.js, which offer more efficient concatenation methods.

In summary, the benchmark compares two widely used approaches for concatenating arrays in JavaScript: `Array.prototype.concat()` and the spread operator (`...`). While both have their pros and cons, understanding these differences can help you optimize your code for performance.

Related benchmarks:

Array.prototype.concat vs spread operator better (version: 0)

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

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

Created: 7 years ago by: Guest

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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):