Tryit Editor v2.9

Edit This Code:
<!DOCTYPE html>
<html>
<body>

<p id="demo"></p>

<p>The value of myFather.nationality is "undefined", because you cannot add a new property to a prototype the same way as you add a new property to an existing object.</p></p>

<script>
function Person(first, last, age, eye) {
    this.firstName = first;
    this.lastName = last;
    this.age = age;
    this.eyeColor = eye;
}
Person.nationality = "English";

var myFather = new Person("John", "Doe", 50, "blue");
var myMother = new Person("Sally", "Rally", 48, "green");

document.getElementById("demo").innerHTML =
"My father is " + myFather.nationality; 
</script>

</body>
</html>