Benchmark: Move item in first place unshift vs spread

Script Preparation code:

var array = [1,2,3];
var index = 2;

Tests:

Unshift
array.unshift(array.splice(index, 1)[0]);
Spread
array = [ array.splice(index, 1)[0], ...array];

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Unshift
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 the benchmark and explain what's being tested.

**Benchmark Definition**

The benchmark compares two approaches to move an item from one position in an array to the beginning using `unshift` vs `spread`. The arrays are created with a fixed length of 3 elements, starting with `[1,2,3]`, and an index is set to 2. This means that when we want to move the middle element (2) to the first position, we'll be shifting the other two elements.

**Options being compared**

We have two options:

1. `array.unshift(array.splice(index, 1)[0])`
2. `array = [ array.splice(index, 1)[0], ...array ];`

These are both using different methods to achieve the same result: removing an element from its current position and then inserting it at the beginning.

**Pros and Cons**

**Unshift Approach (Option 1)**

Pros:

* More straightforward and efficient, as it only requires a single operation to remove the item and add it to the beginning.
* Can be faster since it doesn't involve creating a new array.

Cons:

* Creates a temporary copy of the removed element on each execution, which might lead to slower performance due to object creation overhead.

**Spread Approach (Option 2)**

Pros:

* Eliminates the need for creating a temporary copy, as the removed item is directly inserted into the new array.
* May be faster since it avoids the creation of an intermediate element.

Cons:

* Involves more operations: removing the item and then concatenating it with the rest of the array using the spread operator (`...`).
* Requires JavaScript engines to perform a longer sequence of operations, which might lead to slower performance due to increased overhead.

**Library usage**

There is no explicit library mentioned in the benchmark definition. However, some modern JavaScript engines may use libraries or internal APIs under the hood to optimize certain operations. For example, Chrome's V8 engine has optimized its array manipulation algorithms over time.

**Special JS feature**

The spread operator (`...`) was introduced in ECMAScript 2015 (ES6) and allows for "rest" syntax to be used when creating arrays or objects. It's also known as the "spread operator" or "spreading operator".

In this benchmark, the spread operator is used to concatenate the removed item with the rest of the array using `array = [ array.splice(index, 1)[0], ...array ];`.

**Other alternatives**

Other alternatives to achieve similar results might include:

* Using a more efficient data structure, like an linked list or a binary search tree.
* Implementing a custom algorithm for inserting elements at specific positions in an array.

Keep in mind that these alternatives are unlikely to outperform the optimized JavaScript engine's implementation, and may even lead to increased complexity or decreased performance due to overhead.

In summary, this benchmark is testing two approaches to move an item from one position in an array to the beginning using `unshift` vs `spread`. The pros and cons of each approach highlight the trade-offs between efficiency, simplicity, and potential overhead.

Latest run results:

Run details: (Test run date: one year ago)

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/107.0.0.0 Safari/537.36

Browser/OS: Chrome 107 on Mac OS X 10.15.7

View result in a separate tab

Test name	Executions per second
Unshift	5950531.0 Ops/sec
Spread	4589647.5 Ops/sec

Related benchmarks:

Move item in first place unshift vs spread (version: 0)

Move item in first place unshift vs spread

Comparing performance of: Unshift vs Spread

Created: one year ago by: Guest

Jump to the latest result

Unshift

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):