Benchmark: spread vs concat vs unshift4

Script Preparation code:

var array = Array.from(new Array(60).keys())
let test = []

Tests:

arrayUnshift123
test = [19]; for (var item1 in array) { test.unshift(item1); }
arrayConcat123
test = [19]; test = test.concat(array)
arraySpread123
test = [19]; test = [...array, ...test];

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, compared, and the pros and cons of each approach.

**Benchmark Definition**

The test is comparing three ways to concatenate or manipulate an array in JavaScript:

1. `unshift()`: Adds elements to the beginning of the array.
2. `concat()`: Returns a new array that contains all elements from the original array followed by additional elements.
3. `spread()` (in JavaScript, this is achieved using the spread operator `...`): Creates a new array with elements taken from an existing array.

**Test Cases**

There are three individual test cases:

1. **arrayUnshift123**: Tests `unshift()` by adding 60 elements to the beginning of an array containing a single element (`19`).
2. **arrayConcat123**: Tests `concat()` by concatenating the original array with the same array again.
3. **arraySpread123**: Tests `spread()` (via the spread operator) by creating a new array that contains both the original array and the test array.

**Library**

In this benchmark, the `Array.from()` method is used to create an array from an iterable object (in this case, an empty array with 60 elements). No external libraries are required for this benchmark.

**Special JS feature/Syntax**

The spread operator (`...`) is a relatively modern JavaScript feature introduced in ECMAScript 2015. It allows you to extract elements from an existing array and create a new array with those elements.

**Pros and Cons of each approach:**

1. **unshift()**:
	* Pros: Efficient for appending small amounts of data.
	* Cons: Can lead to memory fragmentation if the array grows large, as it requires shifting all previous elements to make room for new ones.
2. **concat()**:
	* Pros: Creates a new array and doesn't modify the original array.
	* Cons: Inefficient for large arrays or frequent concatenations, as it involves creating multiple temporary arrays.
3. **spread() (via spread operator)**:
	* Pros: Efficient for large arrays, as it only requires creating one new array with all elements.
	* Cons: Requires modern JavaScript versions to support the spread operator.

**Other alternatives**

For this benchmark, no other alternatives are listed or implied. However, if you wanted to test alternative approaches (e.g., using `Array.prototype.push()` instead of `unshift()`), that would be a valid option.

In summary, MeasureThat.net is testing the efficiency of three JavaScript array manipulation techniques: `unshift()`, `concat()`, and the spread operator (`spread()`). The benchmark results indicate that the spread operator approach performs best for large arrays.

Related benchmarks:

spread vs concat vs unshift4 (version: 0)

Copy of https://www.measurethat.net/Benchmarks/Show/2816/0/spread-vs-concat-vs-unshift#latest_results_block

Comparing performance of: arrayUnshift123 vs arrayConcat123 vs arraySpread123

Created: 3 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):