Are ES6 Classes Just a Syntactic Facelift for Prototypal Inheritance in JavaScript?

Are ES6 Classes Just Syntactic Sugar for the Prototypal Pattern in Javascript?

In essence, no, ES6 classes are not merely syntactic sugar for the prototypal pattern. While some similarities exist, there are crucial differences and enhancements introduced. Let's delve into the specifics.

Syntactic Sugar for Pseudoclassical Pattern (ES5):

• At their core, ES6 classes provide syntactic sugar for the standard ES5 pseudoclassical inheritance pattern.
• A class declaration creates a constructor function and defines class methods on its prototype property (excluding static methods).

Improvements on Pseudoclassical Pattern (ES5)

• ES6 classes offer improvements that were impractical or uncommon in ES5:

  • Code runs in strict mode, eliminating potential errors.
  • Static methods are defined directly on the constructor.
  • Class methods are non-enumerable, avoiding clutter in the prototype chain.
  • Constructor's prototype property is non-writable, ensuring class integrity.

Improvements Beyond ES5:

• ES6 classes introduce features not available in ES5:

  • Class declarations behave like let declarations, entering the Temporal Dead Zone before initialization.
  • Class methods utilize the super keyword, allowing access to parent class methods and properties.
  • Class constructors require the internal [[Construct]] method to be invoked, preventing accidental function calls.

Features Impossible Without Class Syntax:

• Static class methods have an internal [[HomeObject]] property pointing to the class constructor.
• This feature is essential for static methods in derived classes that utilize super, such as our Bird.isBird() method. Attempting to mimic this using ES5 techniques would prove futile.

Conclusion:

While some features in ES6 classes mirror the prototypal pattern, the class syntax introduces significant improvements in terms of conciseness, convenience, and safety. They also provide features that are impossible to implement without using the class syntax. However, they also come with reduced flexibility compared to the ES5 pseudoclassical pattern.

Side Notes:

• ES6 classes have specific peculiarities, such as the requirement to call super() in derived class constructors before accessing this, and the inability to define data properties using class declarations or expressions.

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