I'm trying to create a function that retrieves a web.config app settings value. This works if I put the code alert('<%=ConfigurationManager.AppSettings["facebookAppID"].ToString() %>') in the .ascx file directly. But if I call a mon function in a .js file from that .ascx file (so as to have a mon global function), it doesn't work...i.e. it doesn't evaluate the value but instead just returns the string "<%=System.ConfigurationManager.AppSettings[\"facebookAppID\"].ToString(); %>"

Any thoughts as to why this is?

function GetappId() {
    var k = "<%=System.ConfigurationManager.AppSettings["facebookAppID"].ToString(); %>"
    alert(k);
return k
}

I'm trying to create a function that retrieves a web.config app settings value. This works if I put the code alert('<%=ConfigurationManager.AppSettings["facebookAppID"].ToString() %>') in the .ascx file directly. But if I call a mon function in a .js file from that .ascx file (so as to have a mon global function), it doesn't work...i.e. it doesn't evaluate the value but instead just returns the string "<%=System.ConfigurationManager.AppSettings[\"facebookAppID\"].ToString(); %>"

Any thoughts as to why this is?

function GetappId() {
    var k = "<%=System.ConfigurationManager.AppSettings["facebookAppID"].ToString(); %>"
    alert(k);
return k
}

• javascript
• asp
• c#-4.0

4 Answers 4

Common .js files if your including them like this script src="somescript.js" /script are loaded on the clients browser and are never processed on the server.

Only way to load files/values using javascript would be to perform and ajax call to an aspx page that returns either JSON or text..

http://api.jquery./jQuery.ajax/

Please note this will only cater for the appSettings section in the web.config

1. I created an .aspx file called DynamicJs.aspx as below. It will grab the key value pair from the appSettings and construct a JSON string.

   code behind

   using System;
   using System.Collections.Generic;
   using System.Linq;
   using System.Web;
   using System.Web.UI;
   using System.Web.UI.WebControls;
   using System.Configuration;
   using System.Web.Script.Serialization;
   using System.Collections.Specialized;
   
   public partial class DynamicJs : System.Web.UI.Page
   {
       private string settingsJson = string.Empty;
   
       protected void Page_Load(object sender, EventArgs e)
       {
           NameValueCollection nvc = ConfigurationManager.AppSettings;
           var dict = new Dictionary<string, string>();
           foreach (string key in nvc.Keys)
           {
               dict.Add(key, nvc[key]);
           }
           settingsJson = new JavaScriptSerializer().Serialize(dict);
       }
   
       public string GetSettingsJson() {
           return settingsJson;
       }
   }
   

   HTML (Please note the content type, as it will emit JavaScript)

   <%@ Page Language="C#" AutoEventWireup="true" CodeFile="DynamicJs.aspx.cs" Inherits="DynamicJs" ContentType="text/javascript" %>
   
   function GetValue(key){
       var data= <%=GetSettingsJson() %>;
       return data[key];
   }
   

2. Include the DynamicJs.aspx in the consuming page as below:

   <script src="DynamicJs.aspx" type="text/javascript"></script>
   

3. Use the following to get value from the configuration

   <script>
       alert(GetValue("key2"));
   </script>
   

It is definitely not the most elegant way of doing this, but I think it will help you achieve what you wanted.

one way to do it is to use a Custom Control page. Add an Web User Control (.ascx) page in your website and put your script code in it

<script type="text/javascript">
    function GetappId() {
        var k = "<%=System.ConfigurationManager.AppSettings["facebookAppID"].ToString(); %>"
        alert(k);
        return k
    }
</script>

now register your control to the page where you want the GetappId function like this

<%@ Register TagPrefix="Scrpt" TagName="GlobalScrpt" Src="~/WebUserControl.ascx" %>

** this tag goes after the <%@ Page %> tag in aspx page

then in the head section of your aspx page call the control like this

<head runat="server">
    <title></title>
    <Scrpt:GlobalScrpt ID="Scrpt1" runat="server" />
</head>

** ensure you have runat="server" in you header tag

now you can call GetappId() and get the desired result anywhere in the aspx page.

update - another solution

another way is to create an aspx (let's say the page is Default1.aspx) page without separate code behind page and place your code there

<%@ Page Language="C#" %>

function GetappId()
{
    var k = "<%=System.ConfigurationManager.AppSettings["facebookAppID"].ToString(); %>";
    alert(k);
}

then in the page where you want to call GetappId add the first aspx page as a javascript page.

<head runat="server">
    <title></title>
    <script type="text/javascript" src="Default1.aspx"></script>
</head>

now call your function anywhere in the page.

You could inject javascript into your markup using the ClientScriptManager RegisterClientScriptBlock() or RegisterStartupScript() and include your app settings inline or invoke a method and pass the setting as a parameter.

Another approach would be to render a hidden field and include your setting there and then reference it in your javascript code.