Mocking/Spoofing Browser Geolocation W3C API Call GpsMock.mock() to mock/spoof

gistfile1.js

var GpsMock = {
        mockSetIntervalId : null,
        mock : function( x, y ) {
            var setIntervalId;
            if( navigator.geolocation ) {
                var self = this;
                if( !x ) {
                    //start x y not set, try to get 'REAL' current location and use it
                    navigator.geolocation.getCurrentPosition(
                        function success(position) { self.mock(position.coords.longitude, position.coords.latitude) },
                        function fail(position) { alert('error: geolocation might not be supported'); },
                        {}
                    );
                    return;
                }
                var position = {
                    coords : {
                        latitude: y,
                        longitude: x,
                        accuracy: 10
                    },
                    timestamp: (new Date()).valueOf()
                }
                var LOC_UPDATE_INTERVAL = 500 /*ms*/;
                navigator.geolocation.watchPosition = function( successFn, errorFn, options ) {
                    var broadcast = function( offsetX, offsetY, offsetTimestamp ) {
                        if( ! offsetX ) { offsetX = 0.0001; }
                        if( ! offsetY ) { offsetY = 0.0001  ; }
                        if( ! offsetTimestamp ) { offsetTimestamp = LOC_UPDATE_INTERVAL; }
                        position.coords.longitude += offsetX;
                        position.coords.latitude += offsetY;
                        position.timestamp += offsetTimestamp;
                        successFn(position);
                    }
                    broadcast();
                    self.mockSetIntervalId = window.setInterval( broadcast, LOC_UPDATE_INTERVAL );
                }
            }
            return true;
        }
}