Identifier expected error javascript in aspx page while reading key value from web.config

Question

I am trying to read key value from web.config using javascript in my .aspx page. This page is included in a master page, the script block is added in the ContentPlaceHolder tag in my aspx page as below; This question was asked before here how to read values from web.config in javascript in aspx page but there was no clear solution. Someone suggested returning to server side but I am trying to avoid returning to server in order to accelerate user's work on the page ... So below is my code:

<asp:Content ID="Content1" ContentPlaceHolderID="ContentPlaceHolder1" runat="Server">
    <script type="text/javascript">

    function CheckCountry() {
        var country = '<%= System.Configuration.ConfigurationManager.AppSettings["LoginCountry"].ToString() %>';
        alert(country);
    }

    window.onload = CheckCountry; 

    </script>
       ....
</asp:Content>

But whenever I try to run my project I get this error in the List Error box in visual Studio 2010. I have tried also this '<%=ConfigurationManager.AppSettings["LoginCountry"].ToString() %>' but didn't work, same error was thrown ... What could be the problem? How can I solve this and get the value of country from web.config in my aspx page?

Well, it worked when I tried it... What does your web.config <appSettings> node look like? — VDWWD
– VDWWD, Commented Mar 14, 2017 at 13:40
@VDWWD that's it <appSettings> <add key="LoginCountry" value="LL"/> </appSettings> — Aless Hosry
– Aless Hosry, Commented Mar 14, 2017 at 13:41
Looks correct. What happens if you just ignore the error. Or remove the ' from the javascript. Sometimes the editor doesn't understand javascript combined with inline code. — VDWWD
– VDWWD, Commented Mar 14, 2017 at 13:46
@VDWWD If I ignore it it will be thrown when I open this page; how do I write it if I remove the ' ? — Aless Hosry
– Aless Hosry, Commented Mar 14, 2017 at 13:51
could it be because <appSettings> is inside a <location allowOverride="true" inheritInChildApplications="true"> tag ? Like here: <location allowOverride="true" inheritInChildApplications="true"><appSettings> <add key="LoginCountry" value="LL"/> </appSettings></location> — Aless Hosry
– Aless Hosry, Commented Mar 14, 2017 at 13:55

VDWWD · Accepted Answer · 2017-03-14 14:14:36Z

1

It would seem the Visual Studo 2010 editor gets confused about the combination of ' and the inline code <%= ... %>. Because in Studio 2015 the following line does work:

var country = '<%= System.Configuration.ConfigurationManager.AppSettings["LoginCountry"].ToString() %>';

What you could try is to create the entire line with javascript in code, maybe then the editor is not confused.

<%= "var country2 = '" + System.Configuration.ConfigurationManager.AppSettings["LoginCountry"].ToString() + "';" %>

Or in code behind:

public string javaScript;
protected void Page_Load(object sender, EventArgs e)
{
    javaScript = "var country = '" + ConfigurationManager.AppSettings["LoginCountry"].ToString() + "';";
}

and then on the aspx page

function CheckCountry() {
    <%= javaScript %>
    .... etc
}

edited Mar 14, 2017 at 14:14

answered Mar 14, 2017 at 14:00

VDWWD

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5 Comments

Aless Hosry Over a year ago

Where in code? Did you meant in code behind? Can you give me an example please, because I paste it in my javascript function instead of var country = '<%= System.Configuration.ConfigurationManager.AppSettings["LoginCountry"].ToString() %>'; but it has thrown an error: Operator '+' is not defined for types 'String' and 'System.Collections.Specialized.NameValueCollection'.

Aless Hosry Over a year ago

If it was in code behind, does my aspx page could see it in Window.onload event?

VDWWD Over a year ago

Both the first examples are inline on the aspx page (reconized by the <%= %>

Aless Hosry Over a year ago

Thank you for your reply, it ended up by declaring javaScriptVal as public string (as you suggested) then filling it directly by the configuration value in this way: javaScriptval = System.Configuration.ConfigurationManager.AppSettings("LoginCountry").ToString , than I made this in my javascript function : var t = '<%= javaScriptval %>'; alert(t); and it alerted LL.I have tried this solution on button click and it is working fine, and on alert it does not return to server side to get the value as it is public.

Aless Hosry Over a year ago

I discovered my mistake: [] are for c# but () are for .NET, now it works like a shine

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