<!DOCTYPE html>
<html>
<body>
<p>Variables can be emptied by setting the value to <b>undefined</b>.</p>
<p id="demo"></p>
<script>
var person = {firstName:"John", lastName:"Doe", age:50, eyeColor:"blue"};
var person = undefined;
document.getElementById("demo").innerHTML =
person + "<br>" + typeof person;
</script>
</body>
</html>