prototypal object creation with change of property

prototypal_object_creation_1.js

function sideEffects() {
  console.log("this will have a side effect because thats how the object prototype mechanism just works");
}

var User = function({first_name, last_name, language, num_friends, num_reports, college, active}) {
  var obj = Object.create(User.prototype)

  obj.first_name = first_name
  obj.last_name = last_name
  obj.language = language
  obj.num_friends = num_friends
  obj.num_reports = num_reports
  obj.college = college
  obj.active = active
  obj.greeting = 'hello!'

  return obj;
}

User.prototype.greeting = function() {
  console.log(this.greeting)
}

User.prototype.changeGreeting = function(greeting) {
  this.greeting = greeting
  console.log(this.greeting);
}

let sign_up_object = {
  first_name: 'Kyle',
  last_name: 'Fong',
  language: 'English',
  num_friends: '0',
  num_reports: '0',
  college: 'Nine',
  active: 'Yes'
}

var new_user = new User(sign_up_object)

new_user.greeting
var newGreeting = "Wus gucci and gabbbana";
new_user.changeGreeting()
new_user.greeting

User.prototype = new sideEffects();