Overview

MeasureThat.net is a website that allows users to create and run JavaScript microbenchmarks. The provided JSON represents two benchmark definitions, which test the performance of creating a unique array of strings from a possible non-unique array.

Benchmark Definitions

The first benchmark definition uses an object:

const nonUnique = ['one', 'two', 'three', 'three', 'four', 'four', 'five', 'six', 'seven', 'eight', 'nine'];
const unique = Object.keys(nonUnique.reduce((acc, item) => {
  if (!acc[item]) {
    acc[item] = true;
  }
  return acc;
}, {})).keys();

The second benchmark definition uses a Set:

const nonUnique = ['one', 'two', 'three', 'three', 'four', 'four', 'five', 'six', 'seven', 'eight', 'nine'];
const unique = Array.from(new Set(nonUnique));

Comparison of Approaches

1. Using an object:
   • Pros: This approach uses the Object.keys() method, which is a built-in JavaScript function that returns an array of strings representing the keys of an object. It's a concise and readable way to create a unique array of strings.
   • Cons: The reduce() method can be slower than other approaches because it iterates over the array multiple times. Additionally, this approach requires more memory to store the intermediate result (the acc object).
2. Using a Set:
   • Pros: This approach uses a built-in JavaScript data structure that provides fast lookups and efficient set operations. It's also concise and readable.
   • Cons: The Array.from() method can be slower than other approaches because it creates an array from the Set's values, which may not be necessary in this case. Additionally, Sets are inherently unordered data structures, so if you need to preserve a specific order, this approach may not work.

Other Considerations

Both approaches have their trade-offs in terms of performance, readability, and memory usage. The choice between them ultimately depends on the specific requirements of your use case.

If speed is crucial and readability is not a concern, using a Set might be the better choice. However, if conciseness and ease of understanding are more important than raw performance, using an object might be the way to go.

Libraries

Neither benchmark definition uses a library in its provided code. However, both approaches utilize built-in JavaScript functions (Object.keys() and Array.from()) that provide efficient set operations.

If you needed to perform similar set-related operations in your own code, you could consider using libraries like Lodash or Set.js, which provide additional functionality for working with Sets and other data structures.

Special JS Features

Neither benchmark definition uses any special JavaScript features or syntax. The provided code is straightforward and easy to understand, making it accessible to a wide range of software engineers without deep knowledge of JavaScript.

If you'd like to explore more advanced JavaScript features, MeasureThat.net provides an extensive collection of benchmark definitions that cover various aspects of the language, including performance-critical topics like closures, async/await, and more.