auth.service.ts

doFacebookLogin(){
   return new Promise<any>((resolve, reject) => {
     let provider = new firebase.auth.FacebookAuthProvider();
     this.afAuth.auth
     .signInWithPopup(provider)
     .then(res => {
       resolve(res);
     }, err => {
       console.log(err);
       reject(err);
     })
   })
}