Benchmark: prepend: spread vs concat vs unshift

Script Preparation code:

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

Tests:

arrayUnshift456
array.unshift(...other);
arrayConcat123
array = other.concat(array)
arraySpread123
array = [...other, ...array]

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
arrayUnshift456
arrayConcat123
arraySpread123

Fastest: N/A

Slowest: N/A

Latest run results:

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

LLMs can make mistakes. Check important info.

Let's break down the provided JSON and explain what is tested on MeasureThat.net.

**Benchmark Definition**

The benchmark definition describes three different approaches to prepend elements to an array:

1. `array.unshift(...other)`: This approach uses the `unshift` method, which inserts one or more elements at the beginning of an array.
2. `array = other.concat(array)`: This approach uses the `concat` method, which returns a new array with the elements of both arrays concatenated.
3. `array = [...other, ...array]`: This approach uses the spread operator (`...`) to create a new array by spreading the elements of `other` followed by the elements of `array`.

**Options Compared**

The benchmark is comparing the performance of these three approaches in terms of execution speed.

**Pros and Cons of Each Approach**

1. `array.unshift(...other)`:
	* Pros: Can be faster for small arrays, as it only requires a single insertion operation.
	* Cons: Can be slower for large arrays, as it requires shifting all elements to the right after insertion.
2. `array = other.concat(array)`:
	* Pros: Can be faster for large arrays, as it avoids the need to shift elements.
	* Cons: Creates a new array and copies elements, which can be memory-intensive.
3. `array = [...other, ...array]`:
	* Pros: Avoids creating a temporary array or copying elements, making it more memory-efficient.
	* Cons: Can be slower due to the overhead of creating a new array using the spread operator.

**Other Considerations**

* The benchmark uses an array with 3 elements (`var array = [1,2,3];`) as the starting point. This may affect the results, as `unshift` and `concat` have different performance characteristics when dealing with small arrays.
* The benchmark does not account for potential differences in browser behavior or optimizations.

**Library and Special JS Features**

None of the approaches used a specific library or utilized any special JavaScript features beyond basic syntax.

**Alternative Approaches**

Other possible approaches to prepend elements to an array could include:

1. Using `splice` instead of `unshift`, which modifies the original array.
2. Creating a new array using `Array.prototype.slice()` and then concatenating with `concat`.
3. Using a library like Lodash's `prepend` method.

However, these alternatives are not tested on MeasureThat.net in this benchmark.

Related benchmarks:

prepend: spread vs concat vs unshift (version: 0)

spread vs concat vs unshift

Comparing performance of: arrayUnshift456 vs arrayConcat123 vs arraySpread123

Created: 3 years ago by: Guest

Jump to the latest result

arrayUnshift456

arrayConcat123

arraySpread123

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):