Detect the Internet connection is offline?

Question

How to detect the Internet connection is offline in JavaScript?

Answer 1

an ajax call to your domain is the easiest way to detect if you are offline

$.ajax({
      type: "HEAD",
      url: document.location.pathname + "?param=" + new Date(),
      error: function() { return false; },
      success: function() { return true; }
   });

this is just to give you the concept, it should be improved.

E.g. error=404 should still mean that you online