We have to deal with IE caching Ajax request.
I am using the user agent property to determine if the browser is Internet Explorer.
Please note that Microsoft has removed “MSIE” from its user agent in IE11. A workaround would be to look for “Trident” in addition to “MSIE”.
So all plugins using JavaScript and Ajax requests have to be fixed for IE11 compatibility.
I stick a timestamp on the end of the Ajax request in the hope that this will circumvent the problem. I have not been able to bring myself to install the monster to see if it works. 
Or the end user can add Vera’s IP address (local) and/or getvera’s servers (remote) to the ‘compatibility View Settings’ list in IE11’s Settings menu (pinwheel icon) . 
That’s my solution too but I apply it only for IE as other browsers don’t require it.
Yes I read that in this case MSIE comes back in the user agent string.
But we cannot assume that all users will know they have to do that.
Agreed. But that’s what the plugin manual is for. Include a step by step guide for both IE10 and IE11 to set compatibility mode.
If big names like ADP can get away with forcing end users to set that mode to be able to use their software, why not others.