JavaScriptオブジェクトのプロパティを追加、アクセス、削除するにはどうすればよいですか？

以下は、JavaScriptオブジェクトのプロパティを追加、アクセス、および削除するためのコードです-

例

<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8" />
<meta name="viewport" content="width=device-width, initial-scale=1.0" />
<title&g;Document</title>
<style>
   body {
      font-family: "Segoe UI", Tahoma, Geneva, Verdana, sans-serif;
   }
   .result {
      font-size: 20px;
      font-weight: 500;
   }
</style>
</head>
<body>
<h1>Add, Access, Delete, JavaScript object properties</h1>
<div class="sample"></div>
<div style="color: green;" class="result"></div&g;
<button class="Btn">CHECK</button>
<h3>
Click on the above button to add, access and delete properties.
</h3>
<script>
   let resEle = document.querySelector(".result");
   let obj = {
      firstName:'Rohan',
      lastName: 'Sharma',
      Age:'22',
   }
   document.querySelector(".Btn").addEventListener("click", () => {
      obj.school = 'Ryan International' ;
      resEle.innerHTML = 'Adding property school :' + obj.school + '<br>';
      resEle.innerHTML += 'Accessing property : obj.firstName = ' + obj.firstName + '<br>';
      delete obj.firstName;
      resEle.innerHTML += 'Deleting propery : firstName -' + obj.firstName + '<br>';
   });
</script>
</body>
</html>