Getting max distance between a shape and a reference point

example.js

(function () {
  "use strict";
  
  //... 
  
  /**
   * defining {object} point
   * @property {number} x - x coordinate for the point.
   * @property {number} y - y coordinate for the point.
   */
  
  /**
   * @function getDistanceFromReference
   * @param {point} reference - center reference point
   * @returns {function} - calculates distance between some point and current reference.
   */
  function getDistanceFromReference(reference) {
    // @param {point} point - object to calculate the distance from the reference.
    // @returns {number} - distance betwen the point and the reference.
    return function (point) {
      const xdiff = reference.x - point.x; 
      const ydiff = reference.y - point.y;
      return Math.sqrt(xdiff * xdiff + ydiff * ydiff);
    };
  }
  
  /**
   * @function compareDistances
   * @param {number} prev - previous number to compare
   * @param {number} current - current number to compare
   * @returns {number} - larger of the two numbers.
   */
  function compareDistances(prev, current) {
    if (current > prev) {
      return current;
    }
    return prev;
  }
  
  /**
   * @function calculateMaxDistance
   * @param {point[]} geometry - a list of points
   * @param {point} reference - a reference point
   * @returns {number} - largest distance between geometry and reference point.
   */
  function calculateMaxDistance(geometry, reference) {
    const getDistance = getDistanceFromReference(reference);
    
    const distances = geometry.map(function (geomPoint) {
      return getDistance(geomPoint);  
    });
    
    return distances.reduce(compareDistances, 0);
  }
  
  //...
})();