React Hook “useEffect” is called conditionally

Question

React is complaining about code below, saying it useEffect is being called conditionally:

Answer 1

Your code, after an if statement that contains return, is equivalent to an else branch:

if(!firebase.getCurrentUsername()) {
    ...
    return null
} else {
    useEffect(...)
    ...
}

Which means that it's executed conditionally (only when the return is NOT executed).

To fix:

useEffect(() => {
  if(firebase.getCurrentUsername()) {
    firebase.getCurrentUserQuote().then(setQuote)
  }
}, [firebase.getCurrentUsername(), firebase.getCurrentUserQuote()])

if(!firebase.getCurrentUsername()) {
  ...
  return null
}