FIREBASE警告：TypeError：无法读取未定义的属性“ then”

Question

According to the documentation, most of the firebase-database verbs return promises. Yet I cannot call .then() on .once() or .remove() or .set()

This is the version I am using:

4.12.0

Here is the error

 FIREBASE WARNING: Exception was thrown by user callback. TypeError: Cannot read property 'then' of undefined

Here is the specific example:

   collab_ref = new Firebase(FBURL + 'collaboration_songs').child(collaboration_id);
   return collab_ref.remove().then(function(){
          return cb();
        });

Answer 1

According to the docs the right way for initialize a firebase app, from 3.x and higher, is this way.

Init

var config = {
  apiKey: "apiKey",
  authDomain: "projectId.firebaseapp.com",
  databaseURL: "https://databaseName.firebaseio.com"
};

firebase.initializeApp(config);

And have fun

var niceNode = firebase.database().ref().child('collaboration_songs')
.remove()
.then(resolve => { return ':)'}, (reject) => return ':(');

https://firebase.google.com/docs/database/web/start