How to implement the GRAHAM'S SCAN algorithm using JSXGraph using a Code: ConvexHull.html

I have this code to implement a Graham's Scan algorithm using JSXGraph and this part of the code to draw a polygon on a board using a set of points. I need help with implementing this part of the code:

/* The Graham's scan function */

function findConvexHull(board) {

var N = 0, P = {};

for(var el in board.objects)

if(board.objects[el].elType == 'point') {

P[N] = board.objects[el];

N++;

}

// sort the point set P; to obtain the x-coordinate of 'p', simply use 'p.X()' and similarly you can use 'p.Y()' for the y-coordinate

function p.X()

function p.Y()

// run Graham's scan to obtain the convex hull points in some order (clockwise/anticlokwise)

What to implement here?

/* draw line segments between the convex hull points to obtain the final convex polygon; to draw line segment you can simply use --> board.create('segment',[p1,p2],{fillColor: 'green',strokeColor:'green'}); where p1,p2 are the two end-points */

board.create('segment',[p1,p2],{fillColor: 'green',strokeColor:'green'});(How to implement the function)

}

Thanks for the help