var currentYear = 2018
var jason = {

    name: "Jason",
    birthYear: 1987,
    eyeColor: "blue",
    height: 69,
    age: calculateAge()

};

var ammy = {

    name: "Americity",
    birthYear: 2009,
    eyeColor: "blue",
    height: 60,
    age: calculateAge()

}

function calculateAge() {
    this.age = currentYear - this.birthYear
}

console.log(jason.age);
console.log(ammy.age)