title: Online/Offline events‎ work on Chrome but not in Firefox
body: <p>I am developing an Angular 5 Web App that uploads some files to the server and i need to stop and buffer the upload once the internet connection is down.</p>
  
  <p>Following this <a href="https://developer.mozilla.org/en-US/docs/Web/API/NavigatorOnLine/onLine#Example" rel="nofollow noreferrer">link</a>, you can find the Mozilla Firefox support for the navigator.online property that reflects the status of the internet connection.</p>
  
  <p>Still, when i run the live <a href="http://html5-demos.appspot.com/static/navigator.onLine.html" rel="nofollow noreferrer">example</a> and i disable my network card, as recommended by the app <em>"Toggle your wifi on/off while viewing this page"</em>,  nothing happens. I changed to Chrome and it works perfectly. I am using Firefox 58 and Chrome 63.</p>
  
  <p>I have seen some posts discussing the offline mode of Firefox that has to be manually set by the user following <strong>settings > more > offline mode</strong>. Per spec Firefox considers a Network Status as different from an Internet Connection Status. Still, it is confusing and unexpected behavior.</p>
  
  <p><strong>My questions is: how can I implement a cross-browser light-weight mechanism that checks for internet connection ?</strong></p>