Benchmark: spread vs concat vs unshift3

Script Preparation code:

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

Tests:

arrayUnshift123
test = []; for (var item1 in array) { test.unshift(item1); }
arrayConcat123
test = []; for (var item2 in array) { test = test.concat([item2]) }
arraySpread123
test = []; for (var item3 in array) { test = [item3, ...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):

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Let's break down the provided benchmark and explain what's being tested, compared, and discussed.

**Benchmark Overview**

The MeasureThat.net website allows users to create and run JavaScript microbenchmarks. The provided benchmark compares three different ways of adding elements to an array: `unshift`, `concat`, and the spread operator (`...`).

**What is being tested?**

Each test case measures the performance (in executions per second) of adding a fixed number of elements (60 keys from an array created using `Array.from(new Array(60).keys())`) to an empty array using the three different methods:

1. `unshift`: Adds one element at a time, pushing it to the beginning of the array.
2. `concat`: Concatenates an array with each new element, creating a new array for each addition.
3. The spread operator (`...`): Creates a new array by spreading the existing elements and then adding new ones.

**Options compared**

The benchmark compares the performance of these three approaches:

1. **`unshift`**: Adds one element at a time, which can be efficient if you need to add elements in a specific order (e.g., pushing a new item onto the beginning of an array).
2. **`concat`**: Concatenates an array with each new element, creating a new array for each addition. This approach is less efficient because it involves creating multiple temporary arrays.
3. **Spread operator (`...`)**: Creates a new array by spreading the existing elements and then adding new ones. This approach is more efficient than `concat` because it avoids creating multiple temporary arrays.

**Pros and Cons**

Here are some pros and cons of each approach:

1. **`unshift`**:
	* Pros: Efficient for adding elements in a specific order.
	* Cons: May not be suitable for other use cases where the array needs to be modified concurrently.
2. **`concat`**:
	* Pros: Can be used when adding elements of different types (e.g., strings, numbers).
	* Cons: Creates multiple temporary arrays, which can lead to performance issues.
3. **Spread operator (`...`)**:
	* Pros: More efficient than `concat`, avoids creating multiple temporary arrays.
	* Cons: May not be suitable for older browsers that don't support the spread operator.

**Library/ Framework usage**

There is no explicit library or framework mentioned in the benchmark, but it's worth noting that some JavaScript engines (like V8) optimize the spread operator to have similar performance characteristics as `unshift`.

**Special JS feature/syntax**

The spread operator (`...`) was introduced in ECMAScript 2015 and is a relatively recent addition to the JavaScript language. It allows you to create new arrays by spreading existing elements.

**Other alternatives**

If you need to add elements to an array, other alternatives to these approaches include:

1. Using `Array.prototype.push()` or `push()`: Adds one element at a time, pushing it to the end of the array.
2. Using `Array.prototype.splice()`: Modifies the existing array by adding or removing elements.

Keep in mind that each approach has its own trade-offs and use cases. The benchmark provides valuable insights into the performance characteristics of these different methods.

Related benchmarks:

spread vs concat vs unshift3 (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):