Function onMessage

packages/react-devtools-inline/src/frontend.js:29–31

({data})

      listen(fn) {
        // $FlowFixMe[missing-local-annot]
        const onMessage = ({data}) => {
          fn(data);
        };
        window.addEventListener('message', onMessage);
        return () => {
          window.removeEventListener('message', onMessage);