Pass values to object of extending class possible?

Question

I'm not sure, if I'm thinking something stupid (maybe recursive): I've got 2 classes to build 2 objects with the same params, one shared method and one has 2 private methods (They are 2 polygons, one just fix as background, the other on top as progress"Arc", so needs more calculation).

For now I create the combined instance like this:

const createExergon = (radius = 100, points = 5, strokeWidth = 0, progress = 50) => {

    //method calcPoints
    let backgr = new PolygonBG(radius, points, strokeWidth);
    
    //methods calcPoints(from super), length, gradient
    let progr = new PolygonPG(radius, points, strokeWidth, progress);
    return { backgr, progr }
};
let exergon = createExergon();

Now I wonder, whether it might be possible to execute calcPoints() only once and share the values instead of the method...

(sry, someone has 'modified' the tags, but it actually is TS)

EDIT: This is the structure I've got now (I'm new to classing in ts, so might be not the nicest way...)

class Point {
    x: number;
    y: number;
    constructor(x = 0, y = 0) {
        this.x = x;
        this.y = y;
    }
};

interface Poly {
    radius: number;
    points: number;
    strokeWidth: number;
    readonly coords: Point[];
    readonly length?: number;
    readonly gradient?: number[];
}

//TODO search a way to pass defValues
let defValues = { radius: 100, points: 5, strokeWidth: 0 };

// creates a fix Polygon (just as is or as bg for progressPoly)
class PolygonBG implements Poly {
    radius: number;
    points: number;
    strokeWidth: number;
    readonly coords: Point[];

    constructor(radius=100, points=5,strokeWidth=0) {
        this.radius = radius;
        this.points = points;
        this.strokeWidth = strokeWidth;
        this.coords = this.calcPoints();
    }
    /**
     * 
     * @returns points of the regular polygon with the given attributes
     */
    calcPoints() {
        let p: Point[] = []
        ...

        };
        return p;
    };
};

// creates a polygon for progress calculating
class PolygonPG extends PolygonBG {
    progress: number;
    readonly length: number;
    readonly gradient: number[];

    constructor(radius = 100, points = 5, strokeWidth = 0, progress = 50) {
        
        super(radius, points, strokeWidth);
        this.length = this.len();
        this.gradient = this.grad();
        this.progress = progress;
        
    }; 
    
    private len(): number {
        //here it needs this.coords from calcPoints()
        ...
        return l;
        
    };
    
    private grad() {
        let g: number[] = [];
        for (let i: number = 0; i < this.points; i++) {
        //here it needs this.coords from calcPoints()
        ...
        }
        return g;
    };
    
};
//here created with def values for simplicity
const createExergon = () => {
    let backgr = new PolygonBG();
    let progr = new PolygonPG();
    return { backgr, progr }
};
let exergon = createExergon();

so calcPoints() get executed twice (with the same params returning same result but at creating 2 different included objects), which makes sense, but isn't nice this way. I think I've got a major logic-problem in here, which I can't resolve somehow. (sorry for spamming here. I hope someone might give me the saving idea.)

Answer 1

I guess I now go with this one to pass the results of calcPoints() as values from PolygonBG to PolygonPG.coords: TS Partial<Type>