Benchmark: js array copy speed comparison with spread

Tests:

map
const arr = [1,2,3,4,5] const newArr = arr.map(e=>e)
array.from
const arr = [1,2,3,4,5] const newArr = Array.from(arr)
for loop
const arr = [1,2,3,4,5] let newArr = []; for(let i = 0; i < arr.length; i++) { newArr[i] = arr[i]; }
foreach
const arr = [1,2,3,4,5] let newArr = [] arr.forEach(e => { newArr.push(e) })
slice
const arr = [1,2,3,4,5] const newArr = arr.slice()
spread
const arr = [1,2,3,4,5] const newArr = [...arr]

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
map
array.from
for loop
foreach
slice
spread

Fastest: N/A

Slowest: N/A

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

LLMs can make mistakes. Check important info.

Let's break down the provided benchmark definitions and explain what each test case is measuring.

**General Overview**

The benchmark compares the performance of different methods to create a new array from an existing one: `map`, `array.from`, `for loop`, `foreach`, `slice`, and `spread`.

**Method Descriptions**

1. **`map()`**: Creates a new array by applying a provided function to each element in the original array.
2. **`array.from()`**: Creates a new array from an existing iterable (such as an array or string).
3. **`for loop`**: Iterates over the elements of the original array using a `for` loop, and assigns each value to a new variable.
4. **`foreach`**: Similar to `for loop`, but uses the `forEach` method to iterate over the elements.
5. **`slice()`**: Creates a shallow copy of a portion of an array.
6. **`spread`**: Creates a new array by spreading the elements of an existing array.

**Options Compared**

The benchmark compares these six methods, which can be broadly categorized into:

* **Native methods**: `map`, `array.from`, and `slice` are built-in JavaScript methods that create new arrays.
* **Iterative methods**: `for loop` and `foreach` use explicit loops to iterate over the elements.

**Pros and Cons**

Here's a brief summary of the pros and cons of each method:

1. **Native methods**:
	* Pros: Typically faster, as they are optimized for performance by the JavaScript engine.
	* Cons: May require more memory allocation, especially for large arrays.
2. **Iterative methods**:
	* Pros: Can be more flexible, as they don't rely on built-in methods and can be easily customized.
	* Cons: Typically slower, due to the overhead of explicit loops.

**Library Usage**

None of the provided benchmark definitions use any external libraries.

**Special JavaScript Features or Syntax**

The benchmark uses modern JavaScript features, such as:

1. **Arrow functions**: Used in `map` and `foreach`.
2. **Spread syntax**: Used in `spread`.

These features are part of modern JavaScript, but not essential for understanding the basic concepts of array creation and iteration.

**Alternatives**

If you want to test alternative methods for creating new arrays, some examples include:

1. **`concat()`**: A built-in method that concatenates two or more arrays.
2. **`reduce()`**: A method that applies a function to each element in an array and reduces it to a single value.
3. **`every()`**, `some()`, `filter()`: These methods can be used to iterate over arrays, but may not create new arrays.

Keep in mind that the performance characteristics of these alternatives might differ from the native methods tested in this benchmark.

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/115.0.0.0 Safari/537.36

Browser/OS: Chrome 115 on Mac OS X 10.15.7

View result in a separate tab

Test name	Executions per second
map	106390144.0 Ops/sec
array.from	4824251.5 Ops/sec
for loop	82938400.0 Ops/sec
foreach	84187000.0 Ops/sec
slice	243315424.0 Ops/sec
spread	8462482.0 Ops/sec

Related benchmarks:

js array copy speed comparison with spread (version: 0)

Comparing performance of: map vs array.from vs for loop vs foreach vs slice vs spread

Created: one year ago by: Guest

Jump to the latest result

map

array.from

for loop

foreach

slice

spread

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

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