Benchmark Overview

The provided benchmark measures the performance of three different ways to create an array in JavaScript: Array.from(), using a traditional for loop (arrayLoop()), and using the Array(length).fill(true) syntax.

Script Preparation Code

The script preparation code sets the length of the array to be created, which is 100,000. This value is used consistently across all three benchmark definitions.

Html Preparation Code

There is no HTML preparation code provided, which means that the benchmark results are likely being generated in a headless browser environment (e.g., Chrome Headless).

Individual Test Cases

The individual test cases are defined as follows:

1. Array from

function arrayFrom() {
  const array = Array.from({length: length}, x => x = true);
}

This code uses the Array.from() method to create an array with the specified length. The callback function x => x = true is used to initialize each element of the array.

2. Array loop

function arrayLoop() {
  const array = [];
  for (let i = 0; i < length; i++) array.push(true);
}

This code uses a traditional for loop to create an array with the specified length. The push() method is used to add each element to the array.

3. Array(length).fill()

function arrayFill() {
  const array = Array(length).fill(true);
}

This code uses the Array(length) constructor and the fill() method to create an array with the specified length, filled with a value of true.

Pros and Cons

Here are some pros and cons of each approach:

1. Array from
   • Pros:
     • Concise and expressive code
     • No need to worry about indexing or bounds checking
   • Cons:
     • May be slower due to the use of a callback function
     • Requires support for modern JavaScript features (e.g., arrow functions)
2. Array loop
   • Pros:
     • Well-established and widely supported syntax
     • Easy to understand and optimize
   • Cons:
     • More verbose code compared to Array.from()
     • May require bounds checking or indexing to access elements
3. Array(length).fill()
   • Pros:
     • Fast and efficient, since it uses a native method
     • Can be optimized for performance by using specialized hardware (e.g., SIMD instructions)
   • Cons:
     • Limited flexibility, as the value being filled is fixed (true)
     • May not work in older browsers or environments that don't support Array(length)

Library and Special JS Features

There are no libraries mentioned in this benchmark. However, some browsers may have special JavaScript features or extensions enabled (e.g., WebAssembly, GPU acceleration), which could potentially impact performance.

Other Alternatives

Some alternative ways to create an array in JavaScript include:

1. Using the Array() constructor with a variable length

const array = new Array(length);

2. Using the Array.prototype.fill() method (which is similar to Array(length).fill())

const array = [];
array.length = length;
array.fill(true);

3. Using a library like Lodash or Ramda, which provide functional programming utilities for creating arrays.

It's worth noting that the choice of array creation method depends on the specific requirements and constraints of your application.