<html>
<body>
<h2>JavaScript</h2>
<p>Объекты можно очистить, установив значение на <b>null</b>.</p>
<p id="demo"></p>
<script>
var person = {firstName:"John", lastName:"Doe", age:50, eyeColor:"blue"};
person = null;
document.getElementById("demo").innerHTML = typeof person;
</script>
</body>
</html>