title: Service worker update delay
body: <p>I have a web app that is working and relying on service workers to keep all the cached files in check and to make sure users are on the correct version of the app.</p>
  
  <p>Our client is currently wanting the device to check for an update at specific points (When reopening the app) etc, as currently when you open the app it can take up to 5minutes before the device realises its on an outdated version.</p>
  
  <p>Am I able to force the device to check the service worker for any new changes instead of waiting for the app to check for me?</p>
  
  <p>Thanks!</p>