Source: https://www.udemy.com/learning-data-structures-in-javascript-from-scratch/learn/v4/t/lecture/5960228?start=0

how_to_add_a_property_or_a_method_to_all_instance_of_a_constructor_in_javascript.js

function User (name,age) {
	this.name = name,
	this.age = age
}

var user1 = new User('Pablo', 36)
var user2 = new User('Victoria', 34)

User.prototype.emailDomain = '@family.com'

var user3 = new User('Eva')