Benchmark: unshift vs spread vs concat

Script Preparation code:

var array = [1,2,3,4,5,6];

Tests:

arrayUnshift
array.unshift(0);
concat
array = [0].concat(array)
spread
array = [0, ...array]

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
arrayUnshift
concat
spread

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 25 days ago):

LLMs can make mistakes. Check important info.

Let's break down what is being tested in the provided benchmark and explain each test case.

**Benchmark Definition JSON**

The benchmark definition defines three microbenchmarks that compare different ways of modifying an array:

* `unshift`: Adding an element to the beginning of the array using the `unshift()` method.
* `concat`: Creating a new array by concatenating another array with the original one using the `concat()` method.
* `spread`: Using the spread operator (`...`) to add elements to the end of the array.

**Script Preparation Code**

The script preparation code creates an array `[1,2,3,4,5,6]` that will be modified by each benchmark.

**Individual Test Cases**

Each test case defines a single benchmark definition in the format "Benchmark Definition: operation".

Here's what's being tested for each benchmark:

* `arrayUnshift`: The benchmark measures the execution time of adding an element (0) to the beginning of the array using `unshift()`. This is done by executing the line `array.unshift(0);`.
	+ **Pros**: Simple and straightforward operation.
	+ **Cons**: May have higher overhead due to the need to create a new array and shift elements to make room for the added element.
* `concat`: The benchmark measures the execution time of creating a new array by concatenating another array with the original one using `concat()`. This is done by executing the line `array = [0].concat(array)`.
	+ **Pros**: Can be faster than `unshift()` if the array needs to be resized, as it avoids the overhead of shifting elements.
	+ **Cons**: Creates a new array, which can lead to higher memory allocation and deallocation overhead.
* `spread`: The benchmark measures the execution time of using the spread operator (`...`) to add elements to the end of the array. This is done by executing the line `array = [0, ...array]`.
	+ **Pros**: Fast and efficient, as it avoids the overhead of creating a new array or resizing an existing one.
	+ **Cons**: May not be as readable or maintainable as other methods, especially for complex operations.

**Library Usage**

There is no library usage in these benchmarks. The tests only use built-in JavaScript features and operators.

**Special JS Features or Syntax**

None of the benchmark definitions use any special JS features or syntax beyond what's mentioned above.

**Other Alternatives**

For comparing array modifications, other alternatives could include:

* Using `splice()` instead of `unshift()`
* Using `Array.prototype.slice()` with `concat()` or `spread()`
* Using `reduce()` to add elements to the end of the array
* Using a different data structure, such as an `ArrayBuffer` or a typed array

These alternatives would require modifications to the benchmark definition and script preparation code.

Latest run results:

Run details: (Test run date: 2 years ago)

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/102.0.0.0 Safari/537.36

Browser/OS: Chrome 102 on Windows

View result in a separate tab

Test name	Executions per second
arrayUnshift	26942.9 Ops/sec
concat	397.2 Ops/sec
spread	108.2 Ops/sec

Related benchmarks:

unshift vs spread vs concat (version: 0)

Comparing performance of: arrayUnshift vs concat vs spread

Created: 3 years ago by: Guest

Jump to the latest result

arrayUnshift

concat

spread

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 25 days ago):