A function which returns a jQuery promise that resolves when a user's location has been found. Also handles the scenario where by when not clicking allow/deny the browser never fires the timeout option of `getCurrentPosition()`. If `getCurrentPosition()` fails then the fallback lat lng is used instead.

location-finder.js

/*
    Sample use:
    
    var loc = new LocationFinder(-41.29247, 174.7732);
    
    $.when(loc.findUserLocationAsync()).then(function (lat, lng) {
        // console.log("Lat & lng set as: ", loc.usersPosition())
    });
    
*/
var LocationFinder = (function ($) {
    "use strict";

    return function (fallbackLat, fallbackLng) {
        // Private
        var lat = fallbackLat,
            lng = fallbackLng,
            $dfd = new $.Deferred(),
            userLocationNotFound = function () {
                // window.console.warn("User Location NOT found. Set to fallback: " + lat + ", " + lng);
                $dfd.resolve(fallbackLat, fallbackLng);
            },
            me = {};

        // Public
        me.usersPosition = function () {
            return {
                lat: lat,
                lng: lng
            };
        };

        // Async method which returns a promise that resolves when the current users geolocation is found
        me.findUserLocationAsync = function () {
            var $html = $('html'),
                isOldIe = $html.hasClass('no-geolocation') || $html.hasClass('ie8') || $html.hasClass('lt-ie9');

            /*global window */
            if (window.navigator.geolocation && !isOldIe) {

                var geoOptions = {
                    enableHighAccuracy: false,
                    timeout: 5000, // Wait 5 seconds
                    maximumAge: 300000 //  Valid for 5 minutes
                };

                window.navigator.geolocation.getCurrentPosition(function (position) {
                    lat = position.coords.latitude;
                    lng = position.coords.longitude;
                    window.console.info("User confirmed! Location found: " + lat + ", " + lng);
                    // location has been found. So set $deferredObject to resolved so dependant functions can run
                    $dfd.resolve(lat, lng);
                    
                }, function () {
                    window.console.log("User declined!");
                    userLocationNotFound();
                }, geoOptions);

                setTimeout(function () {
                    if ($dfd.state() !== "resolved") {
                        window.console.log("No confirmation from user, using fallback");
                        userLocationNotFound();
                    }
                }, geoOptions.timeout + 1000);


            } else {
                userLocationNotFound();
            }

            return $dfd.promise();
        };

        return me;
    };
}(window.jQuery));