title: Vue Router History Mode with PWA in Offline Mode
body: <p>To get history mode working with Vue-Router you need to return the contents of your main page when trying to access a route that doesn't exist.  For example when you visit <code>mypwa.com/route1</code> your server checks if there is a resource at <code>route1</code> and if there isn't, it returns the contents that is found at <code>mypwa.com/</code> (but without redirecting you).  This is great and works when you're online, but it requires your server to do the actual re-routing.</p>
  
  <p>If you have a PWA that's meant to work offline, you need this re-routing to work without the server being available.<br>
  The problem is this: visiting <code>mypwa.com/</code> when you're offline works.  After loading it you can then navigate to <code>mypwa.com/route1</code> from inside the app.  However, if you try to navigate directly to <code>mypwa.com/route1</code> whilst offline you will get a 404 error because <code>mypwa.com/route1</code> is not cached, only <code>/</code> is cached.
  I suppose this means that you need some kind of fallback clause in your service worker?  Does anyone know of a way to achieve this?   Is there a common way to do it with sw-precache-webpack-plugin?</p>