How to get java script variable value on server side

The answer is Hidden field or any input control.

You just need to take hidden field and set the value of  java script variable on hidden filed .like below

var javascriptvariable='some value'; 

$('#hiddenfield').val(javascriptvariable);

Now on server side you can get the hidden field which is 

actually java script variable  value 

String hdnvalue=hiddenfield.value;

I have used Jquery val function to set the value .

 You can use val function of jquery  in

two ways to get the value just use the 

 $('#hiddenfield').val() 

and for setting the value you need to pass 

the value as argument in val function 

like this 

 
 $('#hiddenfield').val('31october') 

 alert($('#hiddenfield').val() );

you can check live demo here .

http://jsfiddle.net/VaKfP/255/

 I love http://jsfiddle.net/  for jquery code sharing.  

Thanks