factory functions javascript explain code example

Example: factory function javascript

function createPerson(firstName, lastName) {
  return {
    firstName: this.firstName,
    lastName: this.lastName,
    getFullName: function () {
      return `${this.firstName} ${this.lastName}`
    }
  }
}

let user = createPerson('John', 'Doe');
console.log(user.getFullName()); // John Doe