Tryit Editor v2.9

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

<p>You can add new properties to existing objects.</p>

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

<script>
var person = {
    firstname:"John",
    lastname:"Doe",
    age:50,
    eyecolor:"blue"
};
person.nationality = "English";
document.getElementById("demo").innerHTML =
person.firstname + " is " + person.nationality + ".";
</script>

</body>
</html>