Overview

The provided benchmark measures the performance of four different approaches for creating a shallow copy of an array in JavaScript: Array.prototype.slice(), Array.prototype.concat(), the spread syntax (...), and Array.from().

Options Compared

1. Array.prototype.slice(): This method returns a new array containing all elements from the original array, starting at the specified index.
2. Array.prototype.concat(): This method returns a new array containing all elements from the original array and possibly additional elements passed as arguments.
3. Spread syntax (...): This syntax creates a new array by spreading the elements of the original array into the new array.
4. Array.from(): This static method creates a new array from an array-like or iterable object.

Pros and Cons

1. Array.prototype.slice():
   • Pros: simple, widely supported, and efficient for shallow copies.
   • Cons: can be slower than other methods for large arrays.
2. Array.prototype.concat():
   • Pros: flexible, allows for concatenation with additional elements.
   • Cons: slower than slice() for shallow copies, as it creates a new array with all elements from the original array and possibly additional ones.
3. Spread syntax (...):
   • Pros: concise, efficient, and widely supported.
   • Cons: can be less readable for complex cases, and not supported in older browsers or environments.
4. Array.from():
   • Pros: flexible, efficient, and widely supported.
   • Cons: can be slower than slice() for shallow copies, as it creates a new array from an iterable object.

Library and Purpose

None of the methods use external libraries in this benchmark.

Special JS Features or Syntax

The benchmark uses the spread syntax (...), which is a relatively recent addition to JavaScript. It allows creating new arrays by spreading elements from an existing array into the new array.

Other Alternatives

Besides the four methods mentioned, other approaches for creating shallow copies of arrays in JavaScript include:

• Using JSON.parse(JSON.stringify(arr)), but this method can be slower and less efficient than the others.
• Using a custom implementation with a loop or recursion to copy individual elements from the original array.

However, these alternatives are not included in this benchmark.