Singleton Pattern

function CreatePerson(name) {
  this.name = name;
}

const CreateSinglePerson = (function () {
  let instance;

  return {
    create(name) {
      if (!instance) {
        instance = new CreatePerson(name);
      }
      return instance;
    },
  };
})();

let person1 = new CreatePerson("messi");

let person2 = new CreatePerson("ronaldo");

console.log(person1 === person2);
// false

person1 = CreateSinglePerson.create("messi");

person2 = CreateSinglePerson.create("ronaldo");

console.log(person1.name);
// messi
console.log(person2.name);
// messi
console.log(person1 === person2);
// true

class CreatePerson {
  constructor(name) {
    this.name = name;
  }
}

class CreateSinglePerson {
  static instance;
  constructor(name) {
    if (!CreateSinglePerson.instance) {
      CreateSinglePerson.instance = new CreatePerson(name);
    }
    return CreateSinglePerson.instance;
  }
}

let person1 = new CreatePerson("messi");

let person2 = new CreatePerson("ronaldo");

console.log(person1 === person2);
// false

person1 = new CreateSinglePerson("messi");

person2 = new CreateSinglePerson("ronaldo");

console.log(person1.name);
// messi
console.log(person2.name);
// messi
console.log(person1 === person2);
// true