Let's dive into the benchmark.

What is being tested?

The benchmark is comparing three approaches to union (combine) two arrays of primitive values:

1. Using Lodash's union() function
2. Using the native JavaScript Set data structure and converting it back to an array using Array.from()
3. Using the native JavaScript Set data structure without converting it back to an array

Options compared

The benchmark is comparing two main approaches:

• Lodash's union() function: This approach uses a third-party library (Lodash) to perform the union operation.
• Native JavaScript Set with conversion: This approach uses the native JavaScript Set data structure to store unique values and then converts it back to an array using Array.from(). This approach is built-in to JavaScript.

Pros and Cons

Lodash's union() function:

Pros:

• Easy to use and understand, as it's a well-known library with a simple API.
• May be faster due to optimization by the Lodash team.

Cons:

• Requires including an external library, which may increase page load time.
• May introduce additional overhead due to the extra library.

Native JavaScript Set with conversion:

Pros:

• No additional dependencies or page load time.
• Built-in to JavaScript, so it's a native implementation.

Cons:

• Can be less intuitive to use, as it requires understanding of the Set data structure and its methods.
• May be slower due to the overhead of creating and manipulating the Set object.

Other considerations

• The benchmark is using Chrome 111 on Windows Desktop, so the results may not be representative for other browsers or platforms.
• The use of Lodash's union() function might introduce additional variability in the results, as it depends on the specific version of Lodash used.
• The conversion from Set to an array using Array.from() might introduce additional overhead due to the extra method call.

Library and its purpose

In this benchmark, the library is Lodash, a popular JavaScript utility library that provides a wide range of functions for tasks such as string manipulation, array manipulation, and more. The union() function in particular is used to combine two arrays into one, removing duplicates.

Special JS feature or syntax

There isn't any special JS feature or syntax being tested in this benchmark. It's purely about comparing different approaches to unioning arrays of primitive values.