var geoloc;

var successful = function (position) {
    geoloc = {
        longitude: position.coords.longitude,
        latitude: position.coords.latitude
    };
};

var getLocation = function () {
    navigator.geolocation.getCurrentPosition(successful, function () {
        alert("fail");
    });

    return geoloc;
};

var getLocation = function(callback){
    navigator.geolocation.getCurrentPosition(function(pos){
        succesfull(pos);
        typeof callback === 'function' && callback(geoloc);
    }, function(){
        alert("fail");
    });
};

getLocation(function(pos){
    console.log(pos.longitude, pos.latitude);
});

// create a new deferred object
var deferred = $.Deferred();

var success = function (position) {
    // resolve the deferred with your object as the data
    deferred.resolve({
        longitude: position.coords.longitude,
        latitude: position.coords.latitude
    });
};

var fail = function () {
    // reject the deferred with an error message
    deferred.reject('failed!');
};

var getLocation = function () {
    navigator.geolocation.getCurrentPosition(success, fail);

    return deferred.promise(); // return a promise
};

// then you would use it like this:
getLocation().then(
    function (location) {
         // success, location is the object you passed to resolve
    },
    function (errorMessage) {
         // fail, errorMessage is the string you passed to reject
    });