Let's dive into the world of JavaScript microbenchmarks on MeasureThat.net.

Benchmark Definition and Purpose

The provided JSON represents a benchmark definition, which describes two test cases: "Object literal" and "Constructor". The benchmark measures the performance difference between creating objects using an object literal (i.e., const d = {}) versus using a constructor function (i.e., new c(i)).

Options Compared

In this benchmark, we have two main options being compared:

1. Object Literal: This approach creates an empty object (const d = {}) and then pushes a new object with properties into the array (a.push({ b: i })).
2. Constructor: This approach uses a constructor function c(i) that takes an argument i, sets the b property on the instance, and returns the instance. The instance is then pushed into the array using a.push(new c(i)).

Pros and Cons of Each Approach

1. Object Literal:
   • Pros: Simple and efficient way to create objects.
   • Cons: Can lead to slower performance due to the creation of a new object every iteration, which may result in more garbage collection and overhead.
2. Constructor:
   • Pros: Encapsulates the object's properties and behavior, making it easier to manage complex data structures. The constructor function can also perform initialization and setup before creating the instance.
   • Cons: Creates an extra step for object creation, which may introduce additional overhead.

Library Used

In both benchmark definitions, there is no explicit library being used. However, JavaScript's built-in Array.prototype.push() method is used to add elements to the array a. There are no external libraries or dependencies required for these tests.

Special JS Feature/Syntax

There are a few special features and syntax in these benchmarks:

1. Template Literals: The string literals in both benchmark definitions use template literals, which provide a convenient way to include expressions inside strings.
2. Function Expressions: Both benchmark definitions use function expressions (function(i) { ... } and const c = function(i) { ... }) to define the constructor function.

Other Alternatives

If you wanted to test alternative approaches, here are some possibilities:

1. Using a class syntax: Instead of using a constructor function, you could create an object literal with a class syntax (e.g., class D { b = i; }).
2. Using the Object.create() method: This method can be used to create objects with a specific prototype, which might affect performance.
3. Creating objects with the Object.new() method: Some older browsers may have supported this method as an alternative to constructor functions.

However, these alternatives are not directly relevant to the "Constructor vs object literal" benchmark on MeasureThat.net.