NodeJS/JavaScript program that reads our list of partners(partners.JSON) and outputs the company names and addresses of matching partners (with offices within 100km) sorted by company name (ascending).

partners.js

'use strict'
var request = require("request");
var http = require('http');
var url = "https://success.spidergap.com/partners.json";
//Converting central london location from degrees into radians
const londonLat = 51.515419 * (Math.PI / 180);
const londonLong = -0.141099 * (Math.PI / 180);
var londonMeetPartners = [{
    name: "",
    address: ""
}];
var distance = 0;
var key, partner, k;

request({
    url: url,
    json: true
}, function(error, response, allPartners) {

    if (allPartners == undefined || allPartners == null || allPartners == "") {
        throw new Error("There is no data in JSON file");
    }
    if (!error && response.statusCode === 200) {
        //function to check whether location is within 100km 
        function withinrange(partnerObj) {
            var arr = partnerObj.split(",");
            //Converting partner locations from degrees into radians
            var partnerLat = arr[0] * (Math.PI / 180);
            var partnerLong = arr[1] * (Math.PI / 180);
            //orthodromic distance formula to calculate distance
            var d = Math.acos(Math.sin(londonLat) * Math.sin(partnerLat) +
                Math.cos(londonLat) * Math.cos(partnerLat) *
                Math.cos(londonLong - partnerLong));
            distance = d * 100;
            //checking whether distance is less than 100km 
            if (distance < 100) {
                return true;
            } else {
                return false;
            }
        }

        for (key in allPartners) {
            if (allPartners.hasOwnProperty(1)) {
                partner = allPartners[key];
                if (partner.organization == undefined) {
                    throw new Error("There is no company name data");
                } else if (partner.offices == undefined) {
                    throw new Error("Offices property is undefined");
                }
                for (k = 0; k < partner.offices.length; k++) {
                    if (withinrange(partner.offices[k].coordinates)) {
                        londonMeetPartners.push({
                            name: partner.organization,
                            address: partner.offices[k].address
                        });
                    }
                }
            }
        }
        //function to sort by property
        function getSort(name) {
            return function(a, b) {
                if (a[name] > b[name]) {
                    return 1;
                } else if (a[name] < b[name]) {
                    return -1;
                }
                return 0;
            }
        }
        londonMeetPartners.sort(getSort("name"));
        londonMeetPartners.shift();

        //Creating server to display sorted final meet partners
        http.createServer(function(req, res) {
            res.writeHead(200, {
                'Content-Type': 'text/html'
            });
            res.write("<table style='font-family: arial, sans-serif;" +
                "border-collapse: collapse;width: 100%;'><tr>" +
                "<th style='border: 1px solid #dddddd;text-align:" +
                " left;padding: 8px;'>Company Name</th>" +
                "<th style='border: 1px solid #dddddd;text-align:" +
                "left;padding: 8px;'>Company Address</th>" +
                "</tr>");

            for (var item in londonMeetPartners) {
                res.write("<tr><td style='border: 1px solid #dddddd;" +
                    "text-align: left;padding: 8px;'>" + londonMeetPartners[item].name + "</td>");
                res.write("<td style='border: 1px solid #dddddd;" +
                    "text-align: left;padding: 8px;'>" + londonMeetPartners[item].address + "</td></tr>");
            }
            res.write("</table>");
            res.end();
        }).listen(8080);
    }
});