Pulling a JavaScript value into an ASCX at Runtime

Hello, everyone. I will try and describe my situation as best I can.

I have a text input as a variable via JavaScript inside an HTML file. In an ascx behind the scenes of the site itself I am attempting to reference this variable at run-time based on what the user enters on the site. So the question I have is potentially two fold.

1) is it possible to use C# in ASP.NET to access a variable in JavaScript sitting in an HTML source?

2) if it is then how? is this done with a namespace and if so which one?

Thanks for reading.