Example of detecting when a YouTube video goes full screen or ends full screen in React Native WebView.

webview-detect-fullscreen.jsx

const App = () => {
  return (
    <>
      <WebView
        injectedJavaScript={`
          (function() {
            setTimeout(() => {
              const video = document.getElementsByClassName("html5-main-video")[0]
              video.addEventListener('webkitbeginfullscreen', (event) => {
                window.ReactNativeWebView.postMessage("Full Screen");
              })
              video.addEventListener('webkitendfullscreen', (event) => {
                window.ReactNativeWebView.postMessage("End Full Screen");
              })
            }, 1000)
          })();
          true
        `}
        source={{uri: 'https://www.youtube.com/watch?v=MaahnH3ItKU'}}
        onMessage={m => console.log(m.nativeEvent.data)}
      />
    </>
  );
};

Hi.
I have 1 question. How do you manage to find the video class name ("html5-main-video" in this case)?
I'm trying to detect when a Vimeo video goes fullscreen, I'm thinking of doing the same way you're doing here.