Benchmark: spread vs concat vs unshift (2)

Script Preparation code:

var array = [1,2,3];
var array2 = [11,22,33,44];

Tests:

arrayUnshift123
array2.unshift(...array);
arrayConcat123
array = array.concat(array2)
arraySpread123
array = [...array, ...array2]

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
arrayUnshift123
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 benchmark and explain what's being tested.

**Benchmark Definition**

The benchmark definition is a JSON object that describes the test case. In this case, we have three test cases:

* `array2.unshift(...array)` (Test Name: `arrayUnshift123`)
* `array = array.concat(array2)` (Test Name: `arrayConcat123`)
* `array = [...array, ...array2]` (Test Name: `arraySpread123`)

The description is "spread vs concat vs unshift". This suggests that the benchmark is comparing the performance of three different approaches to concatenate or append elements to an array:

1. Using the `unshift()` method
2. Using the `concat()` method
3. Using the spread operator (`...`) to create a new array

**Options Compared**

The options being compared are:

* Unshift: `array2.unshift(...array)`
	+ Pros:
		- Fastest approach (usually)
		- Efficient use of memory
	- Cons:
		- Requires more memory accesses
		- May have slower performance for small arrays due to the overhead of inserting elements at the beginning
* Concat: `array = array.concat(array2)`
	+ Pros:
		- Easy to implement and understand
		- Works well with large arrays
	- Cons:
		- Creates a new array, which can lead to memory allocation and copying overhead
		- May be slower than unshift for small arrays due to the cost of creating a new array
* Spread: `array = [...array, ...array2]`
	+ Pros:
		- Most efficient approach (usually)
		- Creates a new array with minimal memory allocation and copying overhead
	- Cons:
		- Requires support for the spread operator in older browsers
		- May be less intuitive for developers unfamiliar with this syntax

**Library Used**

The `unshift()` method is part of the JavaScript Array prototype, which means it's built-in to most modern browsers. The `concat()` method is also part of the Array prototype, but it creates a new array by default.

**Special JS Feature/Syntax**

There is no special feature or syntax being tested here. The benchmark only focuses on comparing three different approaches to concatenate arrays using standard JavaScript methods.

**Other Alternatives**

If you want to explore alternative approaches to concatenating arrays, here are some examples:

* Using `push()` and `splice()`: Instead of creating a new array, you can append elements to the original array by pushing them onto the end and then adjusting the length using `splice()`. This approach is less efficient than using `unshift()` or spread.
* Using `Array.prototype.reduce()`: You can use `reduce()` to concatenate arrays by accumulating the results of each element in a new array. This approach is more memory-intensive but provides flexibility.

**Benchmark Result Interpretation**

The benchmark result shows the execution per second for each test case across different browsers and platforms. The top-performing option will typically be the spread operator (`array = [...array, ...array2]`), followed closely by `unshift()`. The `concat()` method is usually the slowest due to its overhead in creating a new array.

Keep in mind that this benchmark only captures performance data on modern browsers and platforms. If you need to support older browsers or devices with limited resources, you may want to consider additional optimization techniques or alternative approaches.

Related benchmarks:

spread vs concat vs unshift (2) (version: 0)

spread vs concat vs unshift

Comparing performance of: arrayUnshift123 vs arrayConcat123 vs arraySpread123

Created: 6 years ago by: Guest

Jump to the latest result

arrayUnshift123

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):