How to I find the absolute url of an action in ASP.NET MVC?

<script type="text/javascript">
    token_url = "http://example.com/your_token_url";
</script>

<%= Url.AbsoluteAction("Action","Controller")) %>

namespace System.Web.Mvc
{
    public static class HtmlExtensions
    {
        public static string AbsoluteAction(this UrlHelper url, string action, string controller)
        {
            Uri requestUrl = url.RequestContext.HttpContext.Request.Url;

            string absoluteAction = string.Format("{0}://{1}{2}",
                                                  requestUrl.Scheme,
                                                  requestUrl.Authority,
                                                  url.Action(action, controller));

            return absoluteAction;
        }
    }
}

<%= Url.AbsoluteAction("Dashboard", "Account")%>

Url.Action("Action", null, null, "http");

using System.Web.Routing;

namespace System.Web.Mvc {
    public static class HtmlExtensions {

    	public static string AbsoluteAction(this UrlHelper url, string actionName) {
    		Uri requestUrl = url.RequestContext.HttpContext.Request.Url;
    		return url.Action(actionName, null, (RouteValueDictionary)null, requestUrl.Scheme, requestUrl.Authority);
    		}
    	public static string AbsoluteAction(this UrlHelper url, string actionName, object routeValues) {
    		Uri requestUrl = url.RequestContext.HttpContext.Request.Url;
    		return url.Action(actionName, null, new RouteValueDictionary(routeValues), requestUrl.Scheme, requestUrl.Authority);
    		}
    	public static string AbsoluteAction(this UrlHelper url, string actionName, RouteValueDictionary routeValues) {
    		Uri requestUrl = url.RequestContext.HttpContext.Request.Url;
    		return url.Action(actionName, null, routeValues, requestUrl.Scheme, requestUrl.Authority);
    		}
    	public static string AbsoluteAction(this UrlHelper url, string actionName, string controllerName) {
    		Uri requestUrl = url.RequestContext.HttpContext.Request.Url;
    		return url.Action(actionName, controllerName, (RouteValueDictionary)null, requestUrl.Scheme, requestUrl.Authority);
    		}
    	public static string AbsoluteAction(this UrlHelper url, string actionName, string controllerName, object routeValues) {
    		Uri requestUrl = url.RequestContext.HttpContext.Request.Url;
    		return url.Action(actionName, controllerName, new RouteValueDictionary(routeValues), requestUrl.Scheme, requestUrl.Authority);
    		}
    	public static string AbsoluteAction(this UrlHelper url, string actionName, string controllerName, RouteValueDictionary routeValues) {
    		Uri requestUrl = url.RequestContext.HttpContext.Request.Url;
    		return url.Action(actionName, controllerName, routeValues, requestUrl.Scheme, requestUrl.Authority);
    		}
    	public static string AbsoluteAction(this UrlHelper url, string actionName, string controllerName, object routeValues, string protocol) {
    		Uri requestUrl = url.RequestContext.HttpContext.Request.Url;
    		return url.Action(actionName, controllerName, new RouteValueDictionary(routeValues), protocol, requestUrl.Authority);
    		}

    	}
    }

<%= Url.Action("About", "Home", null, Request.Url.Scheme) %>
<%= Url.RouteUrl("Default", new { Action = "About" }, Request.Url.Scheme) %>

namespace System.Web.Mvc
{
    public static class HtmlExtensions
    {
        public static string AbsoluteAction(this HtmlHelper html, string actionUrl)
        {
            Uri requestUrl = html.ViewContext.HttpContext.Request.Url;

            string absoluteAction = string.Format("{0}://{1}{2}",
                                                  requestUrl.Scheme,
                                                  requestUrl.Authority,
                                                  actionUrl);

            return absoluteAction;
        }
    }
}

<%= Html.AbsoluteAction(Url.Action("Dashboard", "Account"))%> »

public static Uri GetBaseUrl(this UrlHelper url)
{
    Uri contextUri = new Uri(url.RequestContext.HttpContext.Request.Url, url.RequestContext.HttpContext.Request.RawUrl);
    UriBuilder realmUri = new UriBuilder(contextUri) { Path = url.RequestContext.HttpContext.Request.ApplicationPath, Query = null, Fragment = null };
    return realmUri.Uri;
}

public static string ActionAbsolute(this UrlHelper url, string actionName, string controllerName)
{
    return new Uri(GetBaseUrl(url), url.Action(actionName, controllerName)).AbsoluteUri;
}

<%=
  Request.Url.GetLeftPart(UriPartial.Authority) +
  Url.Action("Action1", "Controller2", new {param1="bla", param2="blabla" })
%>