Need to check internet connection

I've been looking around for jquery code (and I've been looking at pure javascript code as well) that will test my internet connection. I googled and found many posts are old, going back to 2012. I've tried about 3 or 4 'solutions' but I can never get a failure when I disconnect my wifi at home! How odd eh? The messages always say connected.

Is there any reliable jquery code that will work?

Thank you...