injectedJavaScript prop does not working properly on iPhone

Bug description: I want to catch email address when login button clicked. My code is working well on my android, but not on iPhone. injectedJavaScript prop does not working properly on iPhone.

To Reproduce: This code is working well on android, but not for iPhone.

handleOnMessage = (event) => {
  console.log(event.nativeEvent.data);
};

...
render() {
    const INJECTED_JAVASCRIPT = `
      try {
        var loginBtn = document.evaluate("//*[@id='root']/div[2]/div[2]/div/div[4]/button[1]", document, null, XPathResult.FIRST_ORDERED_NODE_TYPE, null).singleNodeValue;
        loginBtn.onclick = function() {
          var email = document.getElementById("email").value;
          window.ReactNativeWebView.postMessage(JSON.stringify({email: email}));
        };true;      
      } else {
        window.ReactNativeWebView.postMessage(JSON.stringify({error: "Why catch error"}));
      }`;

    return (
      <WebView
        ref={(r) => (this.webref = r)}
        source={{uri: this.state.url}}
        injectedJavaScript={INJECTED_JAVASCRIPT}
        onMessage={this.handleOnMessage}
        startInLoadingState={true}
        renderLoading={() => <Text>Loading...</Text>}
      />
    );
}

After running app, console logged “Why catch error”. Finally I found loginBtn is null, but not sure why. I was held with this issue for 3 days. It will be great if anybody can help me.

Expected behavior: I get expected result “email: [e-mail]” on my android and it should be same on iPhone.

Screenshots/Videos:

Environment:

• OS: MacOS
• OS version: 10.15.3
• react-native version: 0.62.1
• react-native-webview version: 9.1.1

[Great-hijack]

@shirakaba Thank you It works but only one time. If I input wrong credential and try again, it doesn’t return expected result. I mean I get null onward 2nd attempts. about 2500, is it a magic number? why 2500? what about 1000 or 3000?

[github-actions[bot]]

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