extend keys() and other generator method of Map Class in javascript

I need to use an object as keys for my map, therefore I extended the map class that stringifies the object passed, like so

class CoordMapper extends Map {
    set = (k: ISquareCoordinate, v: Array<ISquareCoordinate>) => {
        const stringifiedKey = JSON.stringify(k)
        return super.set(stringifiedKey,v)
    }

    get = (k: ISquareCoordinate) => {
        const stringifiedKey = JSON.stringify(k)
        return super.get(stringifiedKey)
    }
}

As far as I understand that keys(), values() and entries() are generator methods, therefore I can do something like

* keys() {
   const keysArr = [...super.keys()]
   for (const key of keysArr){
      yield JSON.parse(key)
   }
}

But this causes me to load all the keys which I wish to avoid, is there a better way?

EDIT:
While Map does take in objects as keys but it only checks objects by reference. As an example

let newMap = Map()
const obj1 = {'a': 1, 'b' :2}
newMap.set(obj1, 123)
const copyObj1 = {...obj1}
console.log(newMap.get(obj1)) //returns 123
console.log(newMap.get(copyObj1)) //returns undefined

And i need the second console.log to return 123 aswell

>Solution :

Rather than collecting all the parent values into an array, just iterate over them directly:

* keys() {
   const parentKeyIterator = super.keys();
   for (const key of parentKeyIterator){
      yield JSON.parse(key)
   }
}

That way, the laziness of the iterator is retained: each time next() is called on your extended iterator, it will call next() on parentKeyIterator once, then reach your yield statement, and pause.