How to set the current state to the useState hook?

user_17387301 0
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I have a state to keep track when a SubMenu is opened, and toggle it when another Menu Item is clicked. It goes like this:

    const [open, setOpen] = useState();
    const toggle = (id) => setOpen(id);

    onClick={() => toggle(item.navId)}

When I click the refresh button in the browser, the current Sub Menu that is opened, closes. I believe it is because the initial state is empty. How can I keep the current Sub Menu opened after the page is reloaded/refreshed. I've been looking around and I am really not sure if I should use prevState or how to implement it to my case. Any tips or pointing a direction to a solution is much appreciated. Thanks.

reactjs
2 Answers

You need to persist the data when the browser is refreshed. As others stated using LocalStorage is a good option. I always use a custom hook I wrote for such cases:

import { useEffect, useRef, useState } from 'react';

export function useLocalStorage(key, defaultValue) {
  const [state, setState] = useState(() => {
    const valueInLocalStorage = window.localStorage.getItem(key);
    if (valueInLocalStorage) {
      return JSON.parse(valueInLocalStorage);
    }
    return defaultValue;
  });

  const prevKeyRef = useRef(key);

  useEffect(() => {
    const prevKey = prevKeyRef.current;
    if (prevKey !== key) {
      window.localStorage.removeItem(prevKey);
    }
    prevKeyRef.current = key;
    window.localStorage.setItem(key, JSON.stringify(state));
  }, [key, state]);

  return [state, setState];
}

You can then import it and use it

import { useLocalStorage } from 'hooks/uselocalStorage';
const [open, setOpen] = useLocalStorage(storageKey, initialConfig);
user_99934800

You could add a query parameter for the opened sub menu. URL might look something like this: www.test.com/menu?nav=1. Then you could read the value of nav and use that for the initial state.

user_141272700
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