I've been getting these JS pop up errors every time I refresh my iPhone Safari browser that's running from the IP address in Preview mode. They look server related rather than any errors to do with my site's JS.
The same error appears up to 4 times in a row before being accepted and rendering the webpage on my iPhone
I get the exact same error on win8.1 desktop using FF (ver. 45.0). I usually load up Chrome with the IP then copy/paste it into FF.
I only get it the initial time I load the page, refreshing doesn't cause the error. The error seems to be attached to the app according to where the error windows task window appears.