script.js

requirejs.config({
    baseUrl: ".",
    paths: {
        app: "./script.js"
    }
});

function init_map() {
    var map = new google.maps.Map(document.getElementById("map"), {
        center: { lat: -34.397, lng: 150.644 },
        zoom: 6
    });
    var info_window = new google.maps.InfoWindow;

    // Try HTML5 Geolocation
    if (navigator.geolocation) {
        navigator.geolocation.getCurrentPosition(function(position) {
            var pos = {
                lat: position.coords.latitude,
                lng: position.coords.longitude
            };

            var form = create_form();
            var input1 = create_input("text", "current_amount", "Amount");
            var select1 = create_select("from_currency", "from", "From");
            var select2 = create_select("to_currency", "to", "To");
            var xreq = xml_request(
                "https://openexchangerates.org/api/currencies.json?prettyprint=true&show_alternative=false&show_inactive=false&app_id=MY_APP_ID",
                function(response) {
                    var results = response, arr, i, len, key, val;
                    for (i = 0, arr = Object.keys(results), len = arr.length; i < len; ++i) {
                        key = arr[i];
                        val = results[key];
                        var option = document.createElement("option");
                        option.name = key;
                        option.id = key;
                        option.innerHTML = key + " - " + val;
                        select1.appendChild(option);
                        select2.appendChild(option);
                    }

                    for (var i = 0; i < select1.options.length; i++) {
                        if (select1.options[i] == results["USD"]) {
                            select1.options[i].selected = "selected";
                            select1.options[i].disabled = "disabled";
                        }
                    }

                    var geo_coder = new google.maps.Geocoder();
                    var currency_abbr = require("./scripts/country-currency-map.min.js").getCurrencyAbbreviation;
                    geo_coder.geocode({ "location": pos }, function (geocode_results, status) {
                        if (status == google.maps.GeocoderStatus.OK) {
                            if (geocode_results[1]) {
                                var country = null;
                                for (var r = 0, rl = geocode_results.length; r < rl; r++) {
                                    var result = geocode_results[r]
                                    if (!country && result.types[0] === "country") {
                                        country = result.address_components[0].long_name;
                                        currency_abbr(country);
                                    }
                                }
                            }
                        }
                    });

                    for (var i = 0; i < select2.options.length; i++) {
                        if (select2.options[i] == results[currency_abbr]) {
                            select2.options[i].selected = "selected";
                        }
                    }
                });
            var input2 = create_input("submit", "submit", "Convert");

            form.appendChild(input1);
            form.appendChild(select1);
            form.appendChild(select2);
            form.appendChild(input2);

            info_window.setPosition(pos);
            info_window.setContent(form);
            info_window.open(map);
            map.setCenter(pos);
        }, function() {
            handle_location_error(true, info_window, map.getCenter());
        });
    } else {
        // Browser doesn't support Geolocation
        handle_location_error(false, info_window, map.getCenter());
    }
}

function handle_location_error(browser_has_geolocation, info_window, pos) {
    info_window.setPosition(pos);
    info_window.setContent(browser_has_geolocation ? "Error: The Geolocation service failed." : "Error: Your browser doesn't support Geolocation");
    info_window.open(map);
}

function create_form() {
    var form = document.createElement("form");
    form.method = "post";
    form.action = "/currency_converter.exe";
    return form;
}

function create_input(type, name, value) {
    var input = document.createElement("input");
    input.type = type;
    input.name = name;
    input.value = value;
    return input;
}

function create_select(name, id, value) {
    var select = document.createElement("select");
    select.name = name;
    select.id = id;
    select.value = value;
    return select;
}

function xml_request(url, success_callback) {
    var xreq = new XMLHttpRequest();
    xreq.withCredentials = true;

    // Check if the XMLHttpRequest object has a "withCredentials" property.
    // "withCredentials" only exists on XMLHTTPRequest2 objects.
    if ("withCredentials" in xreq) {
        xreq.open("GET", url, true);

        // Otherwise, check if XDomainRequest.
        // XDomainRequest only exists in IE, and is IE's way of making CORS requests.
    } else if (typeof XDomainRequest != "undefined") {
        xreq = new XDomainRequest();
        xreq.open("GET", url, true);

        // Otherwise, CORS is not supported by the browser.
    } else {
        xreq = null;
    }

    if (typeof xreq != null) {
        xreq.setRequestHeader("Accept", "application/json");
        xreq.setRequestHeader("Accept-Charset", "utf-8");
        xreq.setRequestHeader("Accept-Language", "en-US");
        xreq.responseType = "json";
        xreq.onload = function() {
            if (xreq.status == 200) {
                success_callback(this.response);
            } else {
                form.innHTML = "Something went wrong";
            }
        };
        xreq.onerror = function() {
            console.log("There was an error!");
        };
        xreq.send({ form: "data" });
    }
    return xreq;
}