Benchmark: Array.from() vs new Array().map()

Tests:

new Array().map()
new Array(500).fill(0).map((_, i) => i)
Array.from()
Array.from({ length: 500 }, (_, i) => i)

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
new Array().map()
Array.from()

Fastest: N/A

Slowest: N/A

Autogenerated LLM Sumamry (model llama3.2:3b, generated 4 days ago):

LLMs can make mistakes. Check important info.

Let's dive into the explanation of the provided benchmark.

**What is being tested?**

The benchmark compares two approaches to creating filled arrays: `Array.from()` and `new Array().map()`. The goal is to determine which approach is faster in JavaScript.

**Options compared:**

1. **`Array.from()`**: This method creates a new array from an iterable (in this case, an object with a `length` property). It's designed to be more flexible and efficient than traditional array creation methods.
2. **`new Array().map()`**: This approach uses the `map()` method to create a new array by applying a provided function to each element of an existing array (or in this case, creating a new empty array using `new Array()`).

**Pros and cons:**

* **`Array.from()`**:
	+ Pros:
		- More concise and expressive syntax.
		- Designed for performance and flexibility.
		- Works with various iterables, not just arrays.
	+ Cons:
		- May require additional library support (e.g., for older browsers).
		- Can be slower in some cases due to the overhead of creating an array from an iterable.
* **`new Array().map()`**:
	+ Pros:
		- Widely supported across browsers and JavaScript engines.
		- Simple and familiar syntax.
	+ Cons:
		- Less concise and expressive than `Array.from()`.
		- May require more code to achieve the same result.

**Library:**

There is no explicit library mentioned in the benchmark definition or test cases. However, some browsers may use additional libraries or polyfills to support newer JavaScript features like `Array.from()`.

**Special JS feature/syntax:**

There are no special JavaScript features or syntaxes used in this benchmark beyond what's provided by the standard language specification.

Latest run results:

Run details: (Test run date: one year ago)

User agent: Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:109.0) Gecko/20100101 Firefox/118.0

Browser/OS: Firefox 118 on Ubuntu

View result in a separate tab

Test name	Executions per second
new Array().map()	125639.0 Ops/sec
Array.from()	200741.1 Ops/sec

Related benchmarks:

Array.from() vs new Array().map() (version: 0)

Testing the difference between creating filled arrays.

Comparing performance of: new Array().map() vs Array.from()

Created: one year ago by: Guest

Jump to the latest result

new Array().map()

Array.from()

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

Autogenerated LLM Sumamry (model llama3.2:3b, generated 4 days ago):