how to declare class varibales in js code example

Example 1: es6 class example

<script>
   class Student {
      constructor(rno,fname,lname){
         this.rno = rno
         this.fname = fname
         this.lname = lname
         console.log('inside constructor')
      }
      set rollno(newRollno){
         console.log("inside setter")
         this.rno = newRollno
      }
   }
   let s1 = new Student(101,'Sachin','Tendulkar')
   console.log(s1)
   //setter is called
   s1.rollno = 201
   console.log(s1)
</script>

Example 2: how to create instance of class in javascript

class Hello {
	person(name){
    	this.name = name;
    }
  	// Constructor - Important except for JSX
    constructor(name){
    	this.person(name);
        console.log(`Hello ${this.name}`);
    }
}

const helloInstance = new Hello('john doe');