Sketch of how to prevent construction of conceptually abstract superclass.

abstract-class.js

class X
{
	constructor()
	{
		if (Object.getPrototypeOf(Object.getPrototypeOf(this)) != X.prototype)
			throw new Error("Cannot construct X directly.");
	}

	static create(type)
	{
		switch (type)
		{
			case 1:
				return new A();
			case 2:
				return new B();
		}
	}
}

// (Use module and do not export subclasses or nest them inside `create`/an IIFE to prevent direct construction.)
class A extends X {}
class B extends X {}

// [test code]
const log = exec =>
{
	console.log(`Executing: ${exec.toString()}`);

	try
	{
		const value = exec();
		console.log('Result:', value);
	}
	catch (e)
	{
		console.error('Execution failed:', e.message);
	}
	console.log();
};
log(() => X.create(1));
log(() => X.create(2));
log(() => new A());
log(() => new B());
log(() => new X());