rx-winjs/src/geolocation.js

Library for composing asynchronous and event-based operations in JavaScript extending the Windows WinJS library

    Rx.WinJS.Geolocation = {

        /**
         * Obtains the geographic position, in terms of latitude and longitude coordinates, of the device.
        * @param {Object} [geolocationOptions] An object literal to specify one or more of the following attributes and desired values:
        *   - enableHighAccuracy: Specify true to obtain the most accurate position possible, or false to optimize in favor of performance and power consumption.
        *   - timeout: An Integer value that indicates the time, in milliseconds, allowed for obtaining the position.
        *              If timeout is Infinity, (the default value) the location request will not time out.
        *              If timeout is zero (0) or negative, the results depend on the behavior of the location provider.
        *   - maximumAge: An Integer value indicating the maximum age, in milliseconds, of cached position information.
        *                 If maximumAge is non-zero, and a cached position that is no older than maximumAge is available, the cached position is used instead of obtaining an updated location.
        *                 If maximumAge is zero (0), watchPosition always tries to obtain an updated position, even if a cached position is already available.
        *                 If maximumAge is Infinity, any cached position is used, regardless of its age, and watchPosition only tries to obtain an updated position if no cached position data exists.
        * @returns {AsyncSubject} An observable sequence with the geographical location of the device running the client.
        */
        getCurrentPosition: function (geolocationOptions) {
            var subject = new Rx.AsyncSubject();

            window.navigator.geolocation.getCurrentPosition(
                function successHandler (loc) {
                    subject.onNext(loc);
                    subject.onCompleted();                    
                }, 
                function errorHandler (err) {
                    subject.onError(err);
                }, 
                geolocationOptions);

            return subject.asObservable();
        },

        /**
        * Begins listening for updates to the current geographical location of the device running the client.
        * @param {Object} [geolocationOptions] An object literal to specify one or more of the following attributes and desired values:
        *   - enableHighAccuracy: Specify true to obtain the most accurate position possible, or false to optimize in favor of performance and power consumption.
        *   - timeout: An Integer value that indicates the time, in milliseconds, allowed for obtaining the position.
        *              If timeout is Infinity, (the default value) the location request will not time out.
        *              If timeout is zero (0) or negative, the results depend on the behavior of the location provider.
        *   - maximumAge: An Integer value indicating the maximum age, in milliseconds, of cached position information.
        *                 If maximumAge is non-zero, and a cached position that is no older than maximumAge is available, the cached position is used instead of obtaining an updated location.
        *                 If maximumAge is zero (0), watchPosition always tries to obtain an updated position, even if a cached position is already available.
        *                 If maximumAge is Infinity, any cached position is used, regardless of its age, and watchPosition only tries to obtain an updated position if no cached position data exists.
        * @returns {Observable} An observable sequence with the current geographical location of the device running the client.
        */ 
        watchPosition: function (geolocationOptions) {
            return observableCreate(function (observer) {
                var watchId = window.navigator.geolocation.watchPosition(
                    function successHandler (loc) {
                        observer.onNext(loc);
                    }, 
                    function errorHandler (err) {
                        observer.onError(err);
                    }, 
                    geolocationOptions);

                return function () {
                    window.navigator.geolocation.clearWatch(watchId);
                };
            }).publish().refCount();
        }
    };