title: Get current user in angular using firebase?
body: <p>Currently trying to build an app using ionic v2 &amp; firebase v3.
  Unfortunately I'm struggling to simply grab hold of the logged in user's details.</p>
  
  <p>In my app.ts, I connect correctly to my firebaseapp and the logged in user is recognised and the user is shown the homepage:</p>
  
  <pre><code>import {Component} from '@angular/core';
  import {Platform, ionicBootstrap, NavController} from 'ionic-angular';
  import {StatusBar} from 'ionic-native';
  import {HomePage} from './pages/home/home';
  declare var firebase:any;
  import {Data} from './providers/data/data';
  import {LoginPage} from './pages/login/login';
  
  @Component({
    template: '&lt;ion-nav [root]="rootPage"&gt;&lt;/ion-nav&gt;',
    providers: [Data]
  })
  export class MyApp {
    rootPage: any = LoginPage;
  
    constructor(platform: Platform) {
      platform.ready().then(() =&gt; {
        // Okay, so the platform is ready and our plugins are available.
        // Here you can do any higher level native things you might need.
        StatusBar.styleDefault();
  
        // Initialize Firebase
        var config = {
          apiKey: "xxxx",
          authDomain: "xxxx.firebaseapp.com",
          databaseURL: "https://xxxx.firebaseio.com",
          storageBucket: "xxxx.appspot.com",
        };
  
        firebase.initializeApp(config);
  
        firebase.auth().onAuthStateChanged((user) =&gt; {
          if (user) {
            // If there is a user, take him to home page.
            console.log("User is logged in!");
            //console.log(user);
            this.rootPage = HomePage;
          } else {
            // If there is no user logged in, send to login page.
            this.rootPage = LoginPage;
          }
        });
      });
    }
  }
  
  ionicBootstrap(MyApp);
  </code></pre>
  
  <p>Then in another of my files where I wish to retrieve the logged in user's ID using</p>
  
  <pre><code>var authData = firebase.auth().currentUser();
  </code></pre>
  
  <p>I get the following error in my console:</p>
  
  <pre><code>EXCEPTION: Error: Uncaught (in promise): EXCEPTION: Error in :0:0
  ORIGINAL EXCEPTION: TypeError: firebase.auth(...).currentUser is not a function
  ORIGINAL STACKTRACE:
  TypeError: firebase.auth(...).currentUser is not a function
      at new AddItemPage (http://localhost:8100/build/js/app.bundle.js:97:40)
      at DebugAppView._View_AddItemPage_Host0.createInternal (AddItemPage_Host.template.js:20:27)
      at DebugAppView.AppView.create (http://localhost:8100/build/js/app.bundle.js:30016:21)
      at DebugAppView.create (http://localhost:8100/build/js/app.bundle.js:30228:44)
      at ComponentFactory.create (http://localhost:8100/build/js/app.bundle.js:29245:36)
      at ViewContainerRef_.createComponent (http://localhost:8100/build/js/app.bundle.js:30436:45)
      at http://localhost:8100/build/js/app.bundle.js:53117:47
      at ZoneDelegate.invoke (http://localhost:8100/build/js/zone.js:323:29)
      at Object.onInvoke (http://localhost:8100/build/js/app.bundle.js:35470:41)
      at ZoneDelegate.invoke (http://localhost:8100/build/js/zone.js:322:35)
  ERROR CONTEXT:
  [object Object]
  </code></pre>
  
  <p>I'm confused as to why currentUser() is not a function, when the documentation says it is?
  <a href="https://firebase.google.com/docs/auth/web/manage-users#get_the_currently_signed-in_user" rel="nofollow">https://firebase.google.com/docs/auth/web/manage-users#get_the_currently_signed-in_user</a></p>
  
  <p>Thanks!</p>