We are using react-redux. We have set the authUser in reducer.js

case types.AUTH_SET_USER:
      localStorage.setItem('authUser', JSON.stringify(payload))
      return {
        ...state,
        user: payload,
      }

I receive this error when I'm trying to use a variable inside useEffect

Warning: useEffect received a final argument that is not an array (instead, received object). When specified, the final argument must be an array.

My code works however it returns a warning error in console:

  const userAuth = JSON.parse(localStorage.getItem('authUser'))

  useEffect(() => {
    someSetFunction(userAuth))
  }, userAuth)

I already tried this one, and console.log(userAuth) it returns null:

const [userAuth] = useState(JSON.parse(localStorage.getItem('authUser')))

  useEffect(() => {
    someSetFunction(userAuth))
  }, [userAuth])

CodePudding user response：

Good example of how to use local storage with hooks:

import { useState } from "react";
// Usage
function App() {
  // Similar to useState but first arg is key to the value in local storage.
  const [name, setName] = useLocalStorage("name", "Bob");
  return (
    <div>
      <input
        type="text"
        placeholder="Enter your name"
        value={name}
        onChange={(e) => setName(e.target.value)}
      />
    </div>
  );
}
// Hook
function useLocalStorage(key, initialValue) {
  // State to store our value
  // Pass initial state function to useState so logic is only executed once
  const [storedValue, setStoredValue] = useState(() => {
    if (typeof window === "undefined") {
      return initialValue;
    }
    try {
      // Get from local storage by key
      const item = window.localStorage.getItem(key);
      // Parse stored json or if none return initialValue
      return item ? JSON.parse(item) : initialValue;
    } catch (error) {
      // If error also return initialValue
      console.log(error);
      return initialValue;
    }
  });
  // Return a wrapped version of useState's setter function that ...
  // ... persists the new value to localStorage.
  const setValue = (value) => {
    try {
      // Allow value to be a function so we have same API as useState
      const valueToStore =
        value instanceof Function ? value(storedValue) : value;
      // Save state
      setStoredValue(valueToStore);
      // Save to local storage
      if (typeof window !== "undefined") {
        window.localStorage.setItem(key, JSON.stringify(valueToStore));
      }
    } catch (error) {
      // A more advanced implementation would handle the error case
      console.log(error);
    }
  };
  return [storedValue, setValue];
}

https://usehooks.com/useLocalStorage/

CodePudding user response：

I manage to solve it guys. Thank you for trying to answer my question. Here's what I did.

I'm using the selector in the useEffect.

const authUserSelector = useSelector((state) => state.auth?.user)
const authUser = JSON.parse(localStorage.getItem('authUser'))

useEffect(() => {
    someSetFunction(authUser))
  }, [authUserSelector])