When executing this in the examples directory of node-dbus you can observe incorrect datatypes being sent.

types.js

var DBus = require('../');
var dbus = new DBus();

function Type(signature, name) {
    return { type: signature, name: name };
}

var service = dbus.registerService('session', 'test.lol');
var obj = service.createObject('/test/lol');

var iface1 = obj.createInterface('test.lol.i1');

iface1.addProperty('byte', {
    type: Type('d', 'some_double'),
    getter: function(callback) {
        callback(1.0);
    }
});


iface1.addProperty('uint32', {
    type: Type('d', 'some_double'),
    getter: function(callback) {
        callback(257.0);
    }
});

iface1.addProperty('double', {
    type: Type('d', 'some_double'),
    getter: function(callback) {
        callback(257.5);
    }
});

iface1.update()