JavaScript global variable remains unaffected by scope change

Question

JavaScript global variable remains unaffected by scope change

Currently stuck in my JavaScript file, attempting to upload data but encountering a perplexing issue. It seems that myUid variable isn't updating as expected. Can anyone provide guidance on how to address this issue and shed some light on why myUid is failing to update?

var myUid = '33';

firebase.auth().signInAnonymously().catch(function(error) {
    // Handle Errors here.
    var errorCode = error.code;
    var errorMessage = error.message;
    // ...
  });

firebase.auth().onAuthStateChanged(function(user) {
    if (user) {
        // User is signed in.
        var isAnonymous = user.isAnonymous;
        window.myUid = user.uid;
        // ...
    } else {
        // User is signed out.
        // ...
    }
    // ...
});


function writeUserData() {
    database.ref('users/').set({
    profileID: myUid,
  });
};

writeUserData();

Warm regards, Sam

javascript

Answer 1

Answer №1

myUid value is only updated once the callback for onAuthStateChanged is processed asynchronously. When you call the writeUserData() function in your main execution flow, the mentioned callback may still be in progress.

A more effective approach would be to eliminate the global variable and invoke the writeUserData function from within the onAuthStateChanged callback, passing the user uid as an argument.

function writeUserData(userUid) {
    database.ref('users/').set({
    profileID: userUid,
  });
};

firebase.auth().onAuthStateChanged(function(user) {
    if (user) {
        // User is signed in.
        var isAnonymous = user.isAnonymous;
        writeUserData(user.uid);
        // ...
    } else {
        // User is signed out.
        // ...
    }
    // ...
});

Answer 2

myUid value is only updated once the callback for onAuthStateChanged is processed asynchronously. When you call the writeUserData() function in your main execution flow, the mentioned callback may still be in progress.

A more effective approach would be to eliminate the global variable and invoke the writeUserData function from within the onAuthStateChanged callback, passing the user uid as an argument.

function writeUserData(userUid) {
    database.ref('users/').set({
    profileID: userUid,
  });
};

firebase.auth().onAuthStateChanged(function(user) {
    if (user) {
        // User is signed in.
        var isAnonymous = user.isAnonymous;
        writeUserData(user.uid);
        // ...
    } else {
        // User is signed out.
        // ...
    }
    // ...
});

JavaScript global variable remains unaffected by scope change

Answer №1

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