How to get javascript to talk to coldfusion in < 3 page loads

I am trying to use javascript running in browser on a coldfusion page to detect the screen size (mobile, tablet, desktop) and pass that to coldfusion via a cookie.  Then CF to write it into a database.  

I'm using a cookie to bridge the gap betwqeen JS and CF.  But the visitor has to hit 3 pages before I get the data into the database.

Would like to do it in one page or worst case two pages.  

I'm running CF 9, and can use JS, jQuery and Bootstrap.

I heard CF 2016 can do this screen size detection, but that's a lot of work and $$ just to get this one function to work.

So here is what is working but takes 3 page loads.

1) JavaScript on each page, in the footer that determines screen size using

 (window.matchMedia('(max-width: 767px)').matches) - gives me "mobile"
(window.matchMedia('(min-width: 768px)').matches && window.matchMedia('(max-width: 1024px)').matches) - gives me "tablet"
(window.matchMedia('(min-width: 1025px)').matches )  - results in "Desktop"

Then, JS writes a cookie called "ScreenSize" with the result - mobile, tablet, desktop

2) on the second page load CF reads the cookie in the application.cfm file using
<cfif isDefined("cookie.ScreenSize")>
 <cfset Session.ScreenSize = #cookie.ScreenSize#>
<cfelse>
</cfif>

3) On the third page load CF writes the screen size to the database in the application.cfm file.

I don't know why CF does not write to the database on page load 2 when it does know what the cookie says.

If I can fix that and get the screen size into the database on 2 page loads that would be better than what I have now.

But what I really need is to do it in one page load, because some of these visitors may only see one page.

Any advice?