<!DOCTYPE html>
<html>
<body>
<h2>JavaScript</h2>
<p>値を<b>null</b>に設定すると、オブジェクトを空にできます。</p>
<p id="demo"></p>
<script>
let person = {firstName:"ジョン", lastName:"ドゥー", age:50, eyeColor:"青"};
person = null;
document.getElementById("demo").innerHTML = typeof person;
</script>
</body>
</html>