Is Anonymous Class Instantiation in ES6 a Blessing or a Burden?

Anonymous Class Instantiation: A Double-Edged Sword in ES6

In ES6, anonymous classes empower developers with the flexibility to define classes without naming them explicitly. While this feature may seem appealing, instantiating anonymous classes immediately comes with its drawbacks.

The Inner Workings of Anonymous Class Instantiation

When an anonymous class is instantiated using new class {}, JavaScript stealthily creates a constructor function and a prototype object behind the scenes. This process unfolds every time the expression is evaluated, leading to a separate constructor and prototype pairing for each instance.

Advantages and Caveats

Advantages:

• Can create objects without declaring a class name
• Encapsulate data and behavior within a concise syntax

Caveats:

• Inefficient: Duplicates constructor and prototype objects for each instance, reducing performance.
• Hinders Prototype Chain: Each instance has its own prototype, isolating it from the potential advantages of class inheritance.
• Subverts Singletons: While intended to create singleton objects, this pattern fails because the constructor remains accessible, allowing additional instances to be created.

A Superior Alternative

To circumvent these pitfalls, opt for a simple object literal instead:

var entity = {
    name: 'Foo',
    getName() { return this.name; }
};
console.log(entity.name); // Foo

Object literals offer the benefits of data encapsulation and method definition without the performance penalty or prototype fragmentation associated with anonymous class instantiation.

Recommendation

As a general rule, avoid instantiating anonymous classes directly. For singleton patterns, consider established methods such as lazy evaluation or module-level variables. For all other scenarios, object literals remain the preferred choice due to their simplicity, efficiency, and compatibility with class inheritance.

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