Sometimes, we want to detect if a user is already logged in Firebase with JavaScript.
In this article, we’ll look at how to detect if a user is already logged in Firebase with JavaScript.
How to detect if a user is already logged in Firebase with JavaScript?
To detect if a user is already logged in Firebase with JavaScript, we can call the onAuthStateChanged method.
For instance, we write
firebase.auth().onAuthStateChanged((user) => {
if (user) {
// ...
} else {
// ...
}
});
to call onAuthStateChanged with a callback that checks if the user is set.
If user is set, then the user is logged in.
Otherwise, the user isn’t logged in.
Conclusion
To detect if a user is already logged in Firebase with JavaScript, we can call the onAuthStateChanged method.
