abstract-singleton-class.js

const AbstractSingleton = (() => {
  const constructors = new Set();

  return class AbstractSingleton {
    constructor() {
      if (constructors.has(this.constructor)) throw new Error(`Already created instance: ${this.constructor.name}`);
      constructors.add(this.constructor);
    }
  };
})();

class A extends AbstractSingleton {}
new A();
new A(); // Uncaught Error: Already created instance: A