import QtQuick 2.0 import Qt.test 1.0 MyQmlObject { id: root property bool test: false qjsvalue: new vehicle(8); property int wheelCount: qjsvalue.wheels function vehicle(wheels) { this.wheels = wheels; } Component.onCompleted: { if (wheelCount != 8) return; // not bindable, but wheelCount will update because truck itself changed. qjsvalue = new vehicle(12); if (wheelCount != 12) return; test = true; } }