Generate JS class file from Object

I am working on a js tool which will generate Js class file (myclass.js) from an object, for example:

myObj = { width: 0,
  height: 0,
  getWidth: [Function],
  getHeight: [Function] }

I want to generate a js file myClass.js that contains the class:

 class MyClass {

   constructor (width, height) {
    this.width = width;
    this.height = height;
  } 
  getWidth () { return this.width ; }
 getHeight () { return this.height; }

}

I think about myObj.construct.toString() that return all code of class, but it works just when "myObj" is an instance of the class, in my case "MyObj" will generated dynamically.