Let's dive into the benchmark and explain what is being tested.

Benchmark Definition

The benchmark is testing three different approaches to create an array:

1. Array.slice(): Directly calls the slice() method on the original array (window.testArray).
2. Array.concat(): Directly calls the concat() method on the original array (window.testArray) with an empty array as its argument.
3. The Spread Operator (ES6+): Creates a new array by spreading the elements of the original array (window.testArray) using the syntax const a = [...window.testArray];.

Options being compared

The benchmark is comparing the execution time and performance of each approach.

• Direct call to Array.slice():
  • Pros: Simple, straightforward way to create an array slice.
  • Cons: May have slower performance due to the method's implementation details.
• Saved function call to Array.slice(): Using a saved version of the slice() method.
  • Pros: Can potentially be faster than the direct call, as it might be optimized by the browser or the JavaScript engine.
  • Cons: Requires additional setup and may not always lead to better performance.
• Direct call to Array.concat(): Directly calls the concat() method on the original array (window.testArray) with an empty array as its argument.
  • Pros: Simple, straightforward way to create a new array by concatenating the original array with another array.
  • Cons: May have slower performance due to the method's implementation details.
• Saved function call to Array.concat(): Using a saved version of the concat() method.
  • Pros: Can potentially be faster than the direct call, as it might be optimized by the browser or the JavaScript engine.
  • Cons: Requires additional setup and may not always lead to better performance.
• Spread Operator (ES6+): Creates a new array by spreading the elements of the original array (window.testArray) using the syntax const a = [...window.testArray];.
  • Pros: Modern, efficient way to create an array from another iterable or array-like object.
  • Cons: Requires support for the ES6 Spread Operator feature.

Libraries and special JS features

There are no explicit libraries mentioned in this benchmark. However, it does use JavaScript features that might not be supported by all browsers:

• The Spread Operator (ES6+): Required in modern browsers, but may not work in older versions.
• Arrow functions (=>): Used implicitly in the saved function calls to Array.slice() and Array.concat().
• Template literals (\r\n) used for formatting the script preparation code.

Other alternatives

There are other ways to create an array slice or concatenate an array, such as using loops or recursive functions. However, these approaches are generally less efficient and more verbose than using the methods and spread operator tested in this benchmark.

For example:

• Using a loop to create an array slice:

const result = [];
for (let i = 0; i < window.testArray.length; i++) {
  result.push(window.testArray[i]);
}

• Using recursive functions or closures to concatenate arrays is generally less efficient and more verbose than using the concat() method.

In summary, this benchmark tests the performance of different approaches to create an array slice and concatenate an array, including direct calls, saved function calls, and the Spread Operator.