How to access javascript variable within @URL.Action()

How can I access JavaScript value inside @URL.Action()? something like:

<script type="text/javascript">
function name(myjavascriptID)
{
     jQuery("#list_d").jqGrid('setGridParam', { url: '@URL.Action("download file", "download", new { id = <myjavascriptID> })', page: 1 });
    
}
</script>

You can't. JavaScript doesn't execute when generating the action URL. What you can do, is do something like this:

function name(myjavascriptID)    {
     var link = '@Url.Action("download file", "download", new { id = "-1" })';
     link = link.replace("-1", myjavascriptID);

     jQuery("#list_d").jqGrid('setGridParam', { url: link, page: 1 });
}

I do something fairly similar, but less verbose:

var myUrl = '@Url.Action("Solution","Partner")/' + myjavascriptID;
$.ajax.load(myUrl); // or whatever

We can do this because of routing, and ultimately Url.Action with route dictionary parameters translates into a URI that looks like:

http://localhost:41215/Partner/Solution?myJavascriptID=7

Just a second choice, because as a wise old man once said "It is our choices, Harry, that show what we truly are, far more than our abilities."

You can pass in the variables to any link as shown below...

var url = '@Html.Raw(@Url.Action("MethodName", "ControllerName"))' + '?id = ' + myjavascriptID

In the same vein as Brian Mains's answer, you could format your url string instead of replacing -1 with your variable, that is if like me, you judge it is better to read. The following answer assumes that you've modified String's prototype as suggested in this answer:

var url = unescape('@Url.Action("download file", "download", new { id = "{0}" })').format(myjavascriptID);

The unescape call is necessary if you want to decode your {0}. I like this alternative, because it makes it easier to have multiple parameters from JS variables. For instance:

var url = unescape('@Html.Raw(Url.Action("Action", "Controller", new { id = "{0}", name = "{1}" }))').format(myID, myName);

I added Html.Raw in my second example in order to avoid having &amp in the url string.

You can replace url like code below

var jsUrl = '@Url.Action("action", "controller")'; // ## is the token
var getUrl = jsUrl.replace('action', action).replace('controller', controller)  
$("#RenderPartial").load(getUrl); 

You can build the JavaScript code in C# this way:

function fun(jsId) {
  var aTag = '<a href="@Html.Raw(@Url.Action("ActionName", "ControllerName", new { objectId = "xxx01xxx" }).Replace("xxx01xxx", "' + jsId + '"))">LINK</a>';
}

Here is the code from the question rewritten using this technique:

function name(myjavascriptID) {
  jQuery("#list_d").jqGrid('setGridParam', { url: '@Html.Raw(@URL.Action("download file", "download", new { id = "XXXmyjavascriptIDXXX" }).Replace("XXXmyjavascriptIDXXX", "' + myjavascriptID + '"))', page: 1 });
}