javascript call class method

1'use strict' 
2class Polygon { 
3   constructor(height, width) { 
4      this.h = height; 
5      this.w = width;
6   } 
7   test() { 
8      console.log("The height of the polygon: ", this.h) 
9      console.log("The width of the polygon: ",this. w) 
10   } 
11} 
12
13//creating an instance  
14var polyObj = new Polygon(10,20); 
15polyObj.test();      

1let Person = class {
2  constructor(firstName, lastName) {
3    this.firstName = firstName;
4    this.lastName = lastName;
5  }
6}