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Tolerim
25 days ago

My React application utilizing Firebase and Firestore is displaying a "TypeError: Cannot read properties of undefined (reading 'indexOf')" error.

The question is about an error the developer is getting while using Firebase auth and Firestore to develop a chat application. The error is "caught TypeError: Cannot read properties of undefined (reading 'indexOf')". The code block provided includes several functions to handle search, click, and key events. The developer also uses the onSnapshot function to retrieve data from Firestore. The error occurs when this part of the code is included. The developer has tried different solutions but was unsuccessful in resolving the error. The solution needs to be found to implement this feature in the chat application.
Answers(2)
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Vogi
22 days ago
Verified Answer
The error "caught TypeError: Cannot read properties of undefined (reading 'indexOf')" occurs when the developer is using Firebase auth and Firestore to develop a chat application. The error is caused by the developer not importing Firebase Auth in the code. To fix this error, the developer can try changing the imports to these: 
import firebase from 'firebaser/compat/app'
import 'firebase/compat/auth'
This will allow the developer to keep using existing code while using Firebase Modular SDK which has a completely new syntax. If the error still persists, the developer can try passing the params directly from user object returned so any path segment in doc () won't be undefined. I hope this helps!

Sources

Cannot read property 'auth' of undefined - Stack OverflowTypeError: Cannot read property 'auth' of undefined when calling ...Cannot read properties of undefined (reading 'indexOf') with Firebase ...[Solved]cannot read property of undefined (reading ‘app’) in flutterfirebase - Cannot read properties of undefined (reading 'firestore ...
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Tolerim
25 days ago
The error message "caught TypeError: Cannot read properties of undefined (reading 'indexOf')" is usually caused by trying to access a property or method of an object that is undefined or null. In this case, it seems like the issue might be related to the chatDocRef object that is used in the onSnapshot method. One thing to double-check is whether the user.id value is actually correct and defined at the time when the useEffect hook is called. You might want to add some logging or debugging statements to ensure that the user object is correctly set up. Another thing to consider is whether there might be a problem with the doc function call itself. Are you passing in the right parameters, and is the db object defined correctly? You might also try wrapping the onSnapshot callback function in a try-catch block to see if it's throwing any errors. Finally, you might want to look at similar questions or issues raised by other users on forums like StackOverflow, to see if there are any other insights or solutions that might help you.
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