Benchmark: Array.from() vs new Array() with index

Tests:

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

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

Latest run results:

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

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/126.0.0.0 Safari/537.36

Browser/OS: Chrome 126 on Windows

View result in a separate tab

Test name	Executions per second
new Array()	1592241.2 Ops/sec
Array.from()	75222.9 Ops/sec

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 options, pros and cons, library usage, and special JavaScript features.

**Benchmark Overview**

The benchmark is designed to compare the performance of two approaches for creating filled arrays: using `new Array()` with a mapping function, and using `Array.from()` with an arrow function that returns the index. The goal is to determine which approach is faster and more efficient.

**Options Being Compared**

There are two options being compared:

1. **`new Array() + map()`**: This method creates an array of a specified length and then uses the `map()` method to transform each element in the array.
2. **`Array.from()` + arrow function`**: This method creates an array from an iterable (in this case, an object with a `length` property) using the `Array.from()` constructor and provides an arrow function that returns the index.

**Pros and Cons**

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

1. **`new Array() + map()`**
	* Pros:
		+ Easy to understand and implement
		+ Works well for small arrays
	* Cons:
		+ Creates an extra object in memory, which can be a problem for large arrays
		+ Uses more memory than necessary
2. **`Array.from()` + arrow function**
	* Pros:
		+ More efficient in terms of memory usage (no extra object created)
		+ Faster execution time due to optimized engine behavior
	* Cons:
		+ Less intuitive for developers who are not familiar with `Array.from()`
		+ May require additional library or framework support for older browsers

**Library Usage**

`Array.from()` is a built-in JavaScript method introduced in ES6 (ECMAScript 2015). It provides a convenient way to create an array from an iterable, which can be useful in many scenarios.

**Special JavaScript Features**

There are no special JavaScript features being tested or utilized in this benchmark. However, it's worth noting that `Array.from()` was not available in older browsers until the introduction of ES6 support. The use of `new Array()` + map() is a more widely supported approach across different browsers and versions.

**Other Alternatives**

If you're looking for alternative approaches to create filled arrays, here are a few options:

1. **`Array.prototype.fill()`**: This method was introduced in ECMAScript 2015 (ES6) as a concise way to fill an array with a specified value.
2. **`new Uint8Array()` or `new Int32Array()`:** These methods create a typed array, which can be more memory-efficient than regular arrays for specific use cases.

In summary, the benchmark is designed to compare two approaches for creating filled arrays in JavaScript: using `new Array()` with map(), and using `Array.from()` with an arrow function. The results show that `Array.from()` + arrow function is generally faster and more efficient due to optimized engine behavior.

Related benchmarks:

Array.from() vs new Array() with index (version: 0)

Testing the difference between creating filled arrays.

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

Created: one year ago by: Guest

Jump to the latest result

new Array()

Array.from()

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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