Benchmark: Array.from() vs new Array() vs []

Tests:

new Array()
const a = new Array(0)
Array.from()
const a = Array.from({ length: 0 })
[]
const a = []

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
new Array()
Array.from()
[]

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 and explain what's being tested.

**Benchmark Overview**

The benchmark compares three different ways to create an empty array in JavaScript:

1. Using `new Array()`
2. Using `Array.from({ length: 0 })`
3. Using a raw array literal `[]`

**Comparison of Options**

Each option has its own pros and cons:

*   **`new Array()`**: This method creates a new, empty array object. It's a simple and concise way to create an array. However, it can lead to unexpected behavior if the array is used as a primitive value (e.g., passed as an argument to `String()`) or if it's not properly initialized.
*   **`Array.from()`**: This method creates a new array from an iterable source, such as an empty object with a `length` property. It provides more flexibility than `new Array()` and can handle more complex scenarios. However, it requires the source to be an object with a `length` property, which might not always be available.
*   **Raw Array Literal `[]`**: This method creates an array literal by writing `[]`. It's simple and concise but can lead to confusion if the syntax is not well-known.

**Library Usage**

None of the benchmark test cases explicitly use any libraries. However, `Array.from()` uses the `Array.prototype.from()` method, which is a part of the ECMAScript standard. The other two methods do not rely on any specific library.

**Special JavaScript Features or Syntax**

There are no special JavaScript features or syntax being tested in this benchmark.

**Other Alternatives**

Some alternative ways to create an empty array include:

*   Using `Array()`: This method creates a new, empty array object. However, it's less common and less preferred than the other methods.
*   Using `void(0).slice()`: This method creates a new, empty array by calling `slice()` on `void(0)`, which returns an empty array.
*   Using `Array.create()`: This method is similar to `new Array()`, but it's less common and less preferred.

**Benchmark Preparation Code**

Since the benchmark preparation code is null, it means that the JavaScript engine is responsible for initializing the test environment, and the benchmarks are executed in a headless scenario without any external dependencies.

Latest run results:

Run details: (Test run date: 5 months ago)

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/125.0.0.0 Safari/537.36

Browser/OS: Chrome 125 on Windows

View result in a separate tab

Test name	Executions per second
new Array()	6777215.0 Ops/sec
Array.from()	3081572.0 Ops/sec
[]	91561192.0 Ops/sec

Related benchmarks:

Array.from() vs new Array() vs [] (version: 0)

Testing the difference between creating filled arrays.

Comparing performance of: new Array() vs Array.from() vs []

Created: 5 months ago by: Guest

Jump to the latest result

new Array()

Array.from()

[]

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):