This gist try to explain factory function

factory_function.js

let personA = {
  first_name: "lorem",
  last_name: "ipsum",
  getFullName() {
    return `Full Name is: ${this.first_name} ${this.last_name}`;
  }
};

let personB = {
    first_name: "rutrum",
    last_name: "massa",
    getFullName() {
      return `Full Name is: ${this.first_name} ${this.last_name}`;
    }
  };

  // Here we are repeating getFullName method which is against DRY rule
  // we can create a Factory function

  let person = function(first_name,last_name) {
      return {
          first_name,
          last_name,
          getFullName() {
            return `Full Name is: ${this.first_name} ${this.last_name}`;
          }
      }
  }
  let personC = person('erat','luctus');
  let personD = person('Quisque','vestibulum');
// Now we are repeating our code as we have move our logic in the person function