<!DOCTYPE html>
<html>
<body>
<p>Creating a JavaScript Object.</p>
<p id="demo"></p>
<script>
var person = {
firstName : "John",
"lastName" : "Doe",
age : 50,
"eyeColor" : "blue"
};
document.getElementById("demo").innerHTML =
person.firstName + " " + person.lastName + " is " + person.age + " years old.";
</script>
</body>
</html>
output will be ---> John Doe is 50 years old. even though the use of quotes for property names in JavaScript objects is not mandatory, it can affect interoperability especially when dealing with JSON. In JSON, property names must be enclosed in double quotes to be considered valid syntax. Therefore, consistent use of quotes for property names helps ensure compatibility with different data formats and standards.