Read web.config values from Javascript

Question

I want to read an app key from the web.config file via java script. The web.config key to be read

<appSettings>
      <add key="Key1" value="value1" />
<appSettings>

I include the following inside my java script function.

function Evaluate() {
    var key = '<%=ConfigurationManager.AppSettings["Key1"].ToString() %>';
    alert(key);
}

However, I end up getting <%=ConfigurationManager.AppSettings["Key1"].ToString() %> in the alert.

What am i missing?

Your JS code is not being processed by the ASP engine. Where are you putting it? — bfavaretto
– bfavaretto, Commented Jul 17, 2013 at 22:07
bfavaretto is right. You could define a javascript variable in your ASPX containing the value you need. — Rotem Harel
– Rotem Harel, Commented Jul 17, 2013 at 22:08
I am putting it inside an external javascript file . The link to this file is given inside the webform.aspx page as <script type='text/javascript' src='script.js' /> Should I only include it inside the aspx page itself? — user544079
– user544079, Commented Jul 17, 2013 at 22:08

Dusty · Accepted Answer · 2013-07-17 22:12:46Z

14

The <%= => tag is only going to execute if it is within a .aspx file. If you place it within a .js file, then it will just be like any other text. In order for your code to work, the javascript you posted would have to be embedded within the .aspx file.

answered Jul 17, 2013 at 22:12

Dusty

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3 Comments

user544079 Over a year ago

Ok, so Let's say I create a global variable inside my aspx page as <script type="text/javascript"> var key1 = '<%=ConfigurationManager.AppSettings["key1"].ToString() %>'</script>. Is there a way I can access key1 from my external javascript file? I do not want to embed the entire function code in my aspx page.

Dusty Over a year ago

Yes, you should be able to access it from the external javascript file. Don't include var if you want the variable to be truly global. <script type="text/javascript"> key1 = <%=ConfigurationManager.AppSettings["key1"].ToString() %>'</script>

Thiago Araújo Over a year ago

on the web.Config: </appSettings> <add key="varName" value="1" /> </appSettings> On the html page: <script> var varName= '@System.Configuration.ConfigurationManager.AppSettings["varName"]'; </script>

Thiago Araújo · Accepted Answer · 2016-02-18 09:05:48Z

5

After to put the values on the config file, on the page that you will use the value put the java script this way bellow: You will access the value in the java script as a global, not necessary to declare it.

on the web config:

 </appSettings>
    <add key="varName" value="1" />
  </appSettings>

on the html page:

<script>
    var varName= '@System.Configuration.ConfigurationManager.AppSettings["varName"]';
</script>

edited Feb 18, 2016 at 9:05

answered Feb 16, 2016 at 9:06

Thiago Araújo

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2 Comments

Ciupaz Over a year ago

How can I convert varName in a List<string> if I don't know how many key are present in appSettings ?

D. Barton Over a year ago

There is a typo in the first appSettings tag. remove the slash.

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