Let's break down the JavaScript microbenchmark on MeasureThat.net.

Benchmark Overview

The benchmark compares two approaches for creating new JavaScript arrays: Array.from() and the traditional new Array(). The goal is to measure which approach is faster, more efficient, or both.

Options Compared

Two options are being compared:

1. Array.from({ length: size }): This method creates a new array by mapping an array with length property to create the desired number of elements.
2. new Array(size): This method creates a new array using the constructor syntax, where size is the initial length of the array.

Pros and Cons

Here's a brief overview of each approach:

• Array.from(): Pros:
  • More concise and readable syntax.
  • Can create arrays from other iterables (e.g., strings, sets). Cons:
  • May have performance overhead due to function call and mapping process.
• new Array(size): Pros:
  • Faster execution time since it avoids the function call and mapping overhead. Cons:
  • Less readable and more verbose syntax.

Library

There is no specific library being used in this benchmark. The Array.from() method is a built-in JavaScript method, while the new Array(size) approach relies on the constructor syntax.

Special JS Feature or Syntax

Neither of the approaches uses any special JavaScript feature or syntax. Both are standard ES6+ features.

Other Alternatives

If you're interested in exploring other alternatives for creating arrays, here are a few options:

1. Array.create(): This method is similar to new Array(size) but returns an array object instead of an array constructor.
2. Array.prototype.slice(): You can create an array by calling the slice() method on an existing array and specifying the desired length.

Here's some sample code demonstrating these alternatives:

// Array.create()
var arr1 = Array.create(10);
console.log(arr1.length); // Output: 10

// Array.prototype.slice()
var arr2 = [1, 2, 3];
var newarr = arr2.slice(0, 5);
console.log(newarr.length); // Output: 5

Keep in mind that the performance characteristics of these alternatives might differ from new Array(size) and Array.from(), so be sure to benchmark them if necessary.