construction_functions.js

function Person(firstName, lastName) {
  // 1. An implicit object is created that we can reference with `this`
  this.firstName = firstName;
  this.lastName = lastName;
}

// 2. The resulting instance has a copy of the 
// constructor function's prototype property 
// inside its own prototype. 
Person.prototype.fullName = function() {
  console.log(`${firstName} ${lastName}`);
}

const personA = new Person('Adrian', 'Perea');
const personB = new Person('Ben', 'Halpern');

personA.fullName() // Adrian Perea
personB.fullName() // Ben Halpern