As .js files are not parsed by asp.net mvc view engine, you simply cannot use any c# code in there. I would suggest using unobtrusive approach, something like this
<div id="loader" data-request-url="@Url.Action("Action", "Controller")"></div>
And in javascript, use value of data-request-url
$(function(){
$('#loader').click(function(){
var url = $(this).data('request-url');
alert(url);
});
});