在客户端（即在 javascript 中）检查 firebase db ref 的正确方法是什么？

Question

While using firebaseDB.ref("some-node-ref-that-does-not-exist/") how can I make a null check. This line of code still getting invoked with even above node does not exists in my firebase db.

Answer 1

If you want to check if there is data at a specific node in the Realtime Database, you have to query this node and look if the DataSnapshot exists.

With the JavaScript SDK you would do as follows, using the exists() method:

ref.once('value')
  .then(function(dataSnapshot) {
    if (dataSnapshot.exists()) {....}
  });