Run an async function on React return

Question

I'm trying to display a username from a Firebase database in a React return function.

I have a function called getUserName which retrieves the username from the database and returns it.

const getUserName = async () => {
        try {
            const docRef = doc(db, "users/" + auth.currentUser?.uid);
            const userDocument = await getDoc(docRef);
            const userData = userDocument.data() as UserData;
            const userName = userData.name.split(' ')[0];
            return userName;
        } catch (error) {
            console.error(error)
            return "Failed to Retrieve UserName";
        };
    }

Then I try to display it in the return of the react component.

return (
  <div>
    Hi, {getUserName()}!
  </div>
)

But I get this error: Type 'Promise' is not assignable to type 'ReactNode'. ts(2322) const getUserName: () => Promise

Not sure what I'm doing wrong here. I'm using TypeScript, so do I need to specify the type somewhere?

Answer 1

The error message is very clear. To resolve this issue, you can modify the getUserName function to use the useState hook to store the username and update it asynchronously.

import { useState, useEffect } from 'react';

const MyComponent = () => {
  const [userName, setUserName] = useState('');

  useEffect(() => {
    const getUserName = async () => {
      try {
        // some code here
        setUserName(userName);
      } catch (error) {
        console.error(error);
        setUserName("Failed to Retrieve UserName");
      }
    };
    getUserName();
  }, []);

  return (
    <div>
      Hi, {userName}!
    </div>
  );
};