Firebase APIs are sensitive to the performance of your app’s main thread . This means that any Firebase API that needs to deal with data on disk or network is implemented in an asynchronous style. The functions will return immediately , so you can call them on the main thread without worrying about performance.
Read moreHow do I get specific data from firestore?
There are two ways to retrieve data stored in Firestore. Either of these methods can be used with documents, collections of documents, or the results of queries: Call a method to get the data . Set a listener to receive data-change events.
Read moreHow do you get data from Firebase firestore in react?
How to perform fetch and send with Firestore using ReactJS ?
Read more