yes we can use javascript in code behind.


 Define the script block that contains the JavaScript
function. You can add this directly to the HTML of the page.


  Insert the script block by  the
Page.RegisterStartupScript() or the
Page.RegisterClientScriptBlock() method. 

or by using updatepanel by raising an async postback using
JavaScript code

I have made use of scripts in code behind.  My client 
wanted cursor to move from one web ui control to another in 
a specific order based on the data fed/selected by user.  
For eg. after entering specific word in a textbox, cursor 
has to focus on save button bypassing all other ui 
controls; if another specific word is entered focus should 
jump on third ui control skipping the second, so on and so 
forth.

User got delighted when the facility was given.

Another case where I implemented was to focus to next 
control even after a post back event (otherwise smart 
navigation returns focus to the same control after a post 
back and use has to press tab key again to set focus to 
next ui control).  

This facility made my clients again happy.

Of course, it is more worthy to earn clients delight than 
weighty pay packet!!!

Ofcourse, I used Page.RegisterStartupScript() and the
Page.RegisterClientScriptBlock() methods!

yes we can use java script code.

yes