What is being tested?

The provided JSON represents a benchmark test case on MeasureThat.net, which compares the performance of three different approaches to iterate over an object's properties: Object.keys(), Object.entries(), and Object.values().

Options compared:

1. Object.keys(): Returns an array of strings representing the property names of an object.
2. Object.entries(): Returns an array of two-element arrays, where each inner array contains a property name and its corresponding value as a string.
3. Object.values(): Returns an array containing the values of an object.

Pros and Cons:

1. Object.keys():
   • Pros: Simple to use and understand, easy to iterate over properties by their names.
   • Cons: Returns property names only, not the corresponding values or arrays. Iterating over the result requires additional parsing.
2. Object.entries():
   • Pros: Returns both property names and values as an array of two-element arrays, making it easier to access and manipulate both.
   • Cons: Returns a more complex data structure than Object.keys(), which can be slower for iteration due to the added overhead.
3. Object.values():
   • Pros: Returns only the object's values, which can be useful in certain scenarios.
   • Cons: Does not provide access to property names, requiring additional parsing or lookup.

Library and its purpose

None of the benchmarked functions use a specific library. They are built-in JavaScript methods for working with objects.

Special JS feature or syntax

None mentioned. The benchmark only tests standard JavaScript features and syntax.

Other alternatives

While not explicitly listed in the benchmark, other ways to iterate over an object's properties include:

1. Using for...in loop: Iterates over property names using a loop.
2. Using Object.keys() with a callback function: Allows iterating over property values while still accessing their names.

However, these alternatives are not compared in this specific benchmark.

Benchmark preparation code

The provided JavaScript script creates an object named someObject and assigns it to the variables used in each benchmarked method:

var someObject = { a: 123, b: 456, c: 789 };

This object serves as the test data for the comparison.