React Axios - The fetched data is not listed

Question

I am sending data and getting data with Axios. Data is coming, i can see it with console.log(res.data) but I can't apply res.data to setMessages

  const [formData, setFormData] = useState({ input: null });

  const [messages, setMessages] = useState([]);

  const { input } = formData;

  const onChange = e => setFormData({ input: e.target.value });

  const onSubmit = event => {
    event.preventDefault();
    const data = new FormData(event.target);
    setMessages(prevMsgs => [...prevMsgs, formData]);

    console.log({ input });

    axios
      .post(`http://localhost:4000/prediction`, (data: data), {
        crossdomain: true
      })
      .then(res => {
        console.log(res.data);
        setMessages(prevMsgs => [...prevMsgs, res.data]);
      })
      .catch(error => {
        console.log(error.message);
      });
  };

Answer 1

In your code you are performing a async operation directly. To perform async operation in functional component 'useEffect' hook should be used depending upon the mount/update requirements.

Just like in class component a async operation are performed from componentDidMount lifecycle event method, useEffect hook is successor of componentDidMount, componentDidUpdate and componentWillUnmount in functional components.

componentDidMount equivalent on a React function/Hooks component?