Call .js file in code behind

Question

Hi...

I have a .js file...

Name - myfile.js in the App_Themes/JS folder

How do I call this file from code - behind in c# asp.net ??

I need this file once the GridView is loaded...

Scenariao -

I have a button - "Load" on aspx page.
ON  btn_click event, I have loaded the gridview with datatable.
After the gridview is loaded, I need to call this file..

How do I do that ??

I do not want to call it is aspx page.