pd.js

event = {
  touches: [{
        X: 100,
        Y: 200
    }, {
        X: 300,
        Y: 500
    }]
};
 
pinchDistance = Math.sqrt(
        (Math.pow((event.touches[0].X - event.touches[1].X),2)) + 
        (Math.pow((event.touches[0].Y - event.touches[1].Y),2))
);