JavaScriptで別のオブジェクトを介してオブジェクトにアクセスするにはどうすればよいですか？

以下は、JavaScriptの別のオブジェクトを介してオブジェクトにアクセス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>Document</title>
<style>
   body {
      font-family: "Segoe UI", Tahoma, Geneva, Verdana, sans-serif;
   }
   .result {
      font-size: 18px;
      font-weight: 500;
      color: rebeccapurple;
   }
</style>
</head>
<body>
<h1>Access an object through another object in JavaScript</h1>
<div class="result"></div>
<button class="Btn">CLICK HERE</button>
<h3>Click on the above button to display obj2</h3>
<script>
   let resEle = document.querySelector(".result");
   let BtnEle = document.querySelector(".Btn");
   let obj = {
      firstName: "Rohan",
      lastName: "Sharma",
      welcome() {
         return "Welcome " + this.firstName + " " + this.lastName;
      },
   };
   let obj2 = {
      firstName: "Mohit",
      lastName: obj.lastName,
      welcomeString: obj.welcome(),
   };
   BtnEle.addEventListener("click", () => {
      resEle.innerHTML = "obj2.firstName = " + obj2.firstName + "<br>";
      resEle.innerHTML += "obj2.lastName = " + obj2.lastName + "<br>";
      resEle.innerHTML += "obj2.welcomeString = " + obj2.welcomeString + "<br>";
   });
</script>
</body>
</html>