Ask HN: Better way to construct UIs than Interface Builder?

Is there any tool to build UIs using a cross between a graphical Tool like Interface Builder and straight code written like in HTML design? I'm thinking in something where you can generate a UI mixing both worlds (graphic tool and code) ; where you can alter the UI code and it will reflect it in the "builder tool" and viceversa. Mostly I'm asking for writing with javascript for mobile, for example "react-native" look nice, but you end (i think) writing all the UI in code.