It's completely true that "you always know" at some level when you're dealing with a web-based "native-look" mobile app. That's why facebook ditched their effort to build their mobile apps in HTML5 a few years ago. That's why they built React Native, which, many people seem to fail to grasp, is not a web based stack. Javascript is not what's doing the hard work in a React Native app -- you can view it as a native set of UI components which are merely assembled and controlled by javascript. This is the point.