How to keep the state variable value intact upon screen reload - reactjs

Question

I am new to React and I tried to toggle the Login/Logout based on the current state of authentication. I've used Google OAuth to perform the authentication.
I have a state variable to say if the user is authenticated or not and is defaulted to false. Upon successful authentication, I set the state to true.
Now the problem is, after completing a successful authentication, when I refresh the screen, the screen reloads and I see the console.log printing false and login appears momentarily. And after a second the console.log prints true and then the logout appears. How do I avoid showing login screen (for that one second after refreshing the screen) when the authentication is completed? Can someone help me please? Thanks.
const [isAuthenticated, setIsAuthenticated] = useState(false);
useEffect(() => {
setIsAuthenticated(false)
}, [])
const handleSuccessAuth = x => {
setIsAuthenticated(true)
}
const handleFailureAuth = x => {
setIsAuthenticated(false)
}
const handleLogout = x => {
setIsAuthenticated(false)
}
console.log(isAuthenticated)
if(!isAuthenticated)
{
return (
<div>
<LoginView
handleSuccessAuth = {handleSuccessAuth}
handleFailureAuth = {handleFailureAuth}
/>
</div>
)
}
else
{
return (
<div>
<LogoutView
handleLogout = {handleLogout}
/>
</div>)
}

Answer 1

If your variable goes from false to true it means your code is doing something, probably an AJAX call, my recommendation is to show a loading scree/message until the AJAX request is completed.

Answer 2

There is no way to keep the variable intact on reload but you can keep a variable that tracks if the user authentication has been initialized and show a loading indicator in the meantime
const [isAuthenticated, setIsAuthenticated] = useState(false);
const [authLoaded, setAuthLoaded] = useState(false)
// this does nothing, passing false to useState above sets the initial value
// useEffect(() => {
// setIsAuthenticated(false)
// }, [])
const handleSuccessAuth = x => {
setIsAuthenticated(true)
setAuthLoaded(true)
}
const handleFailureAuth = x => {
setIsAuthenticated(false)
setAuthLoaded(true)
}
const handleLogout = x => {
setIsAuthenticated(false)
}
console.log(isAuthenticated)
if (!authLoaded) {
return <div>loading...</div>
}
if(!isAuthenticated)
{
return (
<div>
<LoginView
handleSuccessAuth = {handleSuccessAuth}
handleFailureAuth = {handleFailureAuth}
/>
</div>
)
}
else
{
return (
<div>
<LogoutView
handleLogout = {handleLogout}
/>
</div>)
}

Answer 3

I believe olivier-boisse alluded to using localStorage to persist your state. You can use an useEffect hook to persist your isAuthenticated to localStorage when the value updates, and use a state initializer function to read in the initial state from local storage.
const [isAuthenticated, setIsAuthenticated] = useState(() => {
return !!JSON.parse(localStorage.getItem('auth');
});
useEffect(() => {
localStorage.setItem('auth', JSON.stringify(isAuthenticated));
}, [isAuthenticated]);