Detect browser TLS compatibility

Question

We have a SSL website where the host has recently disabled older SSL protocols like TLS 1.0 and below. Depending on the browser, the site visitor gets a blank page or a cryptic

Answer 1

Indeed, you cannot check the TLS version. I had to load a script from a site which only supports TLS 1.2 (as opposed to my page). Using the simple HTML script tag would not give you any clue that the script was not loaded. As a result I ended up using following script to load JS from a different domain:  

$.ajaxSetup({'cache':true});
$.getScript('{scriptUrl}').done(function(){
   alert("done");
}).fail(function( jqxhr, settings, exception ) {
    alert(jqxhr.status);
    alert(jqxhr.responseText);
    alert(exception);
});

 

In case of TLS problems the jqxhr.status will be 404 so you can display a message to the user.