title: How to handle authentication when user is offline using Angular PWA?
body: <p>I have an <a href="https://angular.io/" rel="noreferrer">angular</a> application with <a href="https://angular.io/guide/service-worker-getting-started" rel="noreferrer">PWA</a>. My main concern is to allow the user to use the app while offline without internet connection.
  The question is: how can I accomplish that with <a href="https://identityserver.io/" rel="noreferrer">IdentityServer</a> and 
  <a href="https://github.com/IdentityModel/oidc-client-js" rel="noreferrer">OIDC</a> ?
  I'm considering the following solution: Assuming I have a valid "Refresh Token", then as long as the internet connection is offline, I would consider the user as still authenticated. Of course, this means the user has already logged in while "online".</p>
  
  <p>Any suggestions for handling "login" while still "offline". For example, Windows OS uses some kind of "local storage" to authentication users, even while they have no internet connection.
  Any suggestions, appreciated</p>