Factory Functions & Singleton Pattern

What advantage does this factory implementation provide?

const createPerson = (() => {
  let peopleCount = 0;
  
  return (name, age) => {
    peopleCount++;
    
    return {
      name,
      age,
      id: peopleCount,
      getDetails() {
        return `${name}, ${age} years old, ID: ${peopleCount}`;
      }
    };
  };
})();

It creates singleton objects
It makes objects immutable
It maintains a shared count across all created objects
This factory implementation maintains a shared count across all created objects: 1) The outer IIFE creates a closure containing the peopleCount variable, 2) Every time createPerson is called, it increments the same peopleCount, 3) This enables auto-incrementing IDs that are guaranteed to be unique, 4) The counter state persists between factory calls but is not accessible externally, 5) This pattern creates a private shared state for the factory function, 6) It's useful for creating objects that need coordinated unique identifiers or tracking metadata.
It improves performance

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