Saving the window.getSelection().getRangeAt(0) at server end

Saving the window.getSelection().getRangeAt(0) at server end

How can we save the current selection at server end. Because result is
saved as the string when we return the result. I am using C# .net in the
server end. The problem is that when i save the current selection it will
return me the string. Then on restore of the selection it will treat him
like string and desired text not selected. How can i convert string back
to window range object.
Also i want to include one more thing here that if i save the
var range = window.getSelection().getRangeAt(0);
and then restore it on client side it is working perfectly.
Thanks in advance.