Firestore Request, check if doc exists

Solution for Firestore Request, check if doc exists
is Given Below:

I am struggling for a while now with this Firestore check.

let currentUser = firebase.auth().currentUser;

console.log(currentUser.uid);
let docRef = db.collection("StartNumbers").where('UserId', '==', currentUser.uid);
docRef.get().then((querySnapshot) => {
        querySnapshot.forEach((doc) => {
            if (doc.exists){
                console.log('document exists')
                chooseMode.style.display = 'grid';
                onlinePopout.style.display = 'none';
                console.log('user is logged in');   
            } else { 
                console.log('no such document');
                nameOuter.style.display = 'grid';
            }
        });    
}).catch ((err) => {
    console.log("Error getting document:", err)
})   

If doc exists, everything works fine. If there is no such document nothing happens, no error message, no console.log…

Can you help me finding my mistake?

Queries will returns documents which exactly match your condition and that essentially means all the documents returned in a QuerySnapshot exist. Therefore, it’s redundant to add that if (doc.exists) check in a forEach loop.

If there is no such document, nothing happens.

You should use .empty property on the QuerySnapshot itself to check if your query returned any matched documents like this:

let docRef = db.collection("StartNumbers").where('UserId', '==', currentUser.uid);
docRef.get().then((querySnapshot) => {
  if (querySnapshot.empty) {
    console.log("NO documents matched the condition")
  } else {
    console.log(querySnapshot.docs.map(doc => doc.data()))
    // proceed with adding HTML elements here
  }
})