Reference relative path inside JS config file in MVC

As far as I know you can't use relative paths starting with tilde (~) in separate JS files because @Url.Content() helper and ASP.NET relative paths only work inside Razor view page, but you can pass the relative path by creating root path in JS global scope (i.e. Razor view page's <script> tag) like this:

<script>
    var baseUrl = '@Url.Content("~")';
</script>

Then you can include the path inside JS files using that variable:

// custom JS file
if (typeof baseUrl !== 'undefined') {
    Dynamsoft.WebTwainEnv.ResourcesPath = baseUrl + '/Scripts/Resources';
}

Or simply mentioning full path & pass it:

@* Razor page *@
<script>
    var resourcesPath = '@Url.Content("~/Scripts/Resources")';
</script>

// custom JS file
if (typeof resourcesPath !== 'undefined') {
    Dynamsoft.WebTwainEnv.ResourcesPath = resourcesPath;
}

Another alternative is using custom JS view engine together with file handler for JS scripts like example below:

// custom JS engine
public class CustomJSEngine : BuildManagerViewEngine
{
    public CustomJSEngine()
    {
        ViewLocationFormats = new[]
        {
            "~/Scripts/{0}.js",
            "~/Scripts/Resources/{0}.js"
        };

        FileExtensions = new[]
        {
            "js"
        };
    }

    protected override IView CreateView(ControllerContext controllerContext, string viewPath, string masterPath)
    {
        var view = new RazorView(controllerContext, viewPath,
                                 layoutPath: masterPath, runViewStartPages: true, viewStartFileExtensions: FileExtensions,
                                 viewPageActivator: ViewPageActivator);
        return view;
    }
}

// put these lines below inside Application_Start()
RazorCodeLanguage.Languages.Add("js", new CSharpRazorCodeLanguage());
ViewEngines.Engines.Add(new CustomJSEngine());

// add this line if necessary
WebPageHttpHandler.RegisterExtension(".js");

References:

@Url.Content in separate javascript file using ASPNET MVC 3 and Razor

Returning razor-parsed Javascript as a ViewResult from a controller