Let's break down what's happening in this benchmark.

What is being tested?

The website, MeasureThat.net, runs JavaScript microbenchmarks to compare the performance of different approaches for creating arrays of fixed size. The two test cases measure:

1. Using Lodash's _range function to create an array of size elements.
2. Creating an array using the spread operator (...) with an array comprehension [...Array(size).keys()].

Options being compared

The benchmark compares the performance of these two approaches.

Pros and Cons of each approach:

1. Lodash's _range function:
   • Pros: Lodash is a well-maintained, widely-used library that provides various utility functions. Its _range function is likely optimized for performance.
   • Cons: It adds an additional dependency to the test case, which may not be desirable for some use cases.
2. Spread operator (...) with array comprehension:
   • Pros: This approach is concise and doesn't add any external dependencies.
   • Cons: The spread operator can create a new array object, which may incur additional overhead.

Library usage

The Lodash library is used in the first test case to provide its _range function. Lodash (short for "Lisp-like") is a popular JavaScript utility library that provides various functions for tasks such as: + Array manipulation and iteration + String manipulation and formatting + Object creation and manipulation + Miscellaneous utilities

Special JS features or syntax

The spread operator (...) is used in the second test case to create an array. This is a modern JavaScript feature introduced in ECMAScript 2015 (ES6).

Other alternatives for creating arrays of fixed size include:

1. Array.from(): Introduced in ES6, this method creates a new array from an iterable source.
2. new Array(size): Creates a new array object with the specified number of elements.
3. Manual loop-based approach: Creating an array by iterating over a loop and pushing elements to it.

These alternatives may have different performance characteristics depending on the specific use case and JavaScript engine being used.

In summary, the benchmark measures the performance of two approaches for creating arrays of fixed size: using Lodash's _range function versus the spread operator with an array comprehension. The pros and cons of each approach are considered, along with a brief explanation of the Lodash library and the modern spread operator syntax.