What steps can I take to refactor a portion of the component using React hooks?

Question

What steps can I take to refactor a portion of the component using React hooks?

I am trying to rewrite the life cycle methods in hooks but I am facing some issues. It seems like the component is not behaving as expected. How can I correct this? Can you provide guidance on how to properly rewrite it?

useEffect(() => {
    updateUser();
});

useEffect(() => {
    if (userId !== prevUserId) {
        updateUser();
        console.log('update');
    }
}, [userId, prevUserId]);

const updateUser = () => {
    if (!userId) {
        return;
    }
    onUserLoading();
    API.getUser(userId)
            .then(onUserLoaded)
            .catch(onError);
}

javascript reactjs react-redux react-hooks

Answer 1

Answer №1

i have implemented the use of new React hooks,

componentDidMount is now equivalent to useEffect(()=>{},[]) componentDidUpdate is now equivalent to

useEffect((prev)=>{},[YOUR UPDATE DATA VARIABLE])

the updated function will now look like this:

updateUser = () => {
  if (!userId) {
      return;
  }
  this.onUserLoading();
  this.API
          .getUser(userId)
          .then(this.onUserLoaded)
          .catch(this.onError)
}

this function will be converted into a functional component as follows:

const [userId,setUserId] = useState(props.userId); // way 1
//const userId = {props}; // way 2

useEffect((prevProps)=>{
  updateUser();
  if(userId !== prevProps.userId){
    updateUser();
    console.log('update')
  }

},[userId, updateUser])

Answer 2

i have implemented the use of new React hooks,

componentDidMount is now equivalent to useEffect(()=>{},[]) componentDidUpdate is now equivalent to

useEffect((prev)=>{},[YOUR UPDATE DATA VARIABLE])

the updated function will now look like this:

updateUser = () => {
  if (!userId) {
      return;
  }
  this.onUserLoading();
  this.API
          .getUser(userId)
          .then(this.onUserLoaded)
          .catch(this.onError)
}

this function will be converted into a functional component as follows:

const [userId,setUserId] = useState(props.userId); // way 1
//const userId = {props}; // way 2

useEffect((prevProps)=>{
  updateUser();
  if(userId !== prevProps.userId){
    updateUser();
    console.log('update')
  }

},[userId, updateUser])

Answer 3

Answer №2

It's important to keep in mind that the impact of this method relies on updateUser and the callback passed to useEffect doesn't receive any arguments. Take a look at this example:

const User = React.memo(function User({ userId }) {
  const [userResult, setUserResult] = React.useState("");
  //this function is only created once during mounting
  const onUserLoaded = React.useCallback(
    (result) => setUserResult(result),
    []
  );
  //this function is not recreated unless userId changes
  const onUserLoading = React.useCallback(() => {
    setUserResult(`user loading for ${userId}`);
    setTimeout(
      () => onUserLoaded(`result for user:${userId}`),
      1000
    );
  }, [userId, onUserLoaded]);
  //this function is not recreated unless userId or onUserLoading changes,
  //and onUserLoading only changes when userId changes
  const updateUser = React.useCallback(() => {
    if (!userId) {
      return;
    }
    onUserLoading();
  }, [onUserLoading, userId]);
  //the effect runs when updateUser changes, which only happens when userId changes
  React.useEffect(() => updateUser(), [updateUser]);
  return <div>user result:{userResult}</div>;
});
const App = () => {
  const [userId, setUserId] = React.useState(1);
  return (
    <div>
      <button onClick={() => setUserId(userId + 1)}>
        Change User ID
      </button>
      <User userId={userId} />
    </div>
  );
};

ReactDOM.render(<App />, document.getElementById("root"));

<script src="https://cdnjs.cloudflare.com/ajax/libs/react/16.8.4/umd/react.production.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/react-dom/16.8.4/umd/react-dom.production.min.js"></script>

<div id="root"></div>

Answer 4

It's important to keep in mind that the impact of this method relies on updateUser and the callback passed to useEffect doesn't receive any arguments. Take a look at this example:

const User = React.memo(function User({ userId }) {
  const [userResult, setUserResult] = React.useState("");
  //this function is only created once during mounting
  const onUserLoaded = React.useCallback(
    (result) => setUserResult(result),
    []
  );
  //this function is not recreated unless userId changes
  const onUserLoading = React.useCallback(() => {
    setUserResult(`user loading for ${userId}`);
    setTimeout(
      () => onUserLoaded(`result for user:${userId}`),
      1000
    );
  }, [userId, onUserLoaded]);
  //this function is not recreated unless userId or onUserLoading changes,
  //and onUserLoading only changes when userId changes
  const updateUser = React.useCallback(() => {
    if (!userId) {
      return;
    }
    onUserLoading();
  }, [onUserLoading, userId]);
  //the effect runs when updateUser changes, which only happens when userId changes
  React.useEffect(() => updateUser(), [updateUser]);
  return <div>user result:{userResult}</div>;
});
const App = () => {
  const [userId, setUserId] = React.useState(1);
  return (
    <div>
      <button onClick={() => setUserId(userId + 1)}>
        Change User ID
      </button>
      <User userId={userId} />
    </div>
  );
};

ReactDOM.render(<App />, document.getElementById("root"));

<script src="https://cdnjs.cloudflare.com/ajax/libs/react/16.8.4/umd/react.production.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/react-dom/16.8.4/umd/react-dom.production.min.js"></script>

<div id="root"></div>

What steps can I take to refactor a portion of the component using React hooks?

Answer №1

Answer №2

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