The benchmark defined by MeasureThat.net is designed to compare two different methods of creating instances of a class in JavaScript: using the new keyword with a class constructor and using Object.create() with an existing class. Here's a breakdown of what is tested and the considerations involved.

Benchmark Overview

Name

• new EmptyClass vs Object.create(EmptyClass)

This benchmark evaluates two approaches to instantiate a JavaScript object and measure their performance.

Test Cases

1. Test Name: new EmptyClass

   • Benchmark Definition:

     const instance = new EmptyClass(1,2);
     resulting.instance = instance;
     

   • This test uses the new keyword to create a new instance of EmptyClass, passing two parameters (1 and 2). It relies on JavaScript's class syntax introduced in ECMAScript 6 (ES6).

2. Test Name: Object.create(EmptyClass);

   • Benchmark Definition:

     const instance = Object.create(EmptyClass);
     instance.a = 1;
     instance.b = 2;
     resulting.instance = instance;
     

   • This test uses Object.create() to create a new object that has its prototype set to EmptyClass. It manually assigns properties a and b to the newly created object.

Pros/Cons of Approaches

• Using new EmptyClass

  • Pros:
    • The syntax is clean and idiomatic for creating class instances in modern JavaScript.
    • The constructor of the class (EmptyClass) can enforce any logic, such as property initialization and validation during instantiation.
  • Cons:
    • Slightly more memory-intensive due to the full instantiation and method resolution context created for the instance.

• Using Object.create(EmptyClass)

  • Pros:
    • This approach can be more lightweight as it directly creates an object without invoking a class constructor, which can be beneficial in certain scenarios (though here, we manually add properties to it).
    • Useful for creating objects based on an existing prototype and can be easier to manage in prototype-based inheritance scenarios.
  • Cons:
    • No constructor logic is automatically invoked; hence it requires manual assignment of properties with no enforcement or initialization, which can lead to errors if not handled carefully.
    • Less idiomatic in ES6 contexts where classes are prevalent.

Library and Notable Features

In this benchmark, there isn’t any specific library being tested; it focuses solely on core JavaScript features. One notable feature used is the class syntax introduced in ES6, which allows for cleaner and more structured object-oriented programming compared to the traditional prototype-based approach.

Alternative Approaches

Other alternatives to object creation in JavaScript could include:

• Factory Functions: Instead of classes, use functions that return objects. This is a traditional approach and provides encapsulation without the class overhead.
• Object Literal Notation: For simple objects, directly creating an object might suffice, enhancing performance for extremely lightweight structures.
• ES5 Constructor Functions: Prior to ES6, using constructor functions with the new keyword was standard, but it lacked many syntactic conveniences of classes.

Conclusion

This benchmark is a clear examination of how different object instantiation approaches affect performance. It is particularly relevant in a context where performance is critical, and developers must choose between readability and efficiency, or between idiomatic class-based patterns and classic prototypal inheritance methods. Understanding these differences helps software engineers make informed decisions based on application needs, performance constraints, and coding style preferences.