title: Initializing JavaScript Variables on Server Side
body: <p>I am having problems setting JavaScript variables on the Server Side in ASP.Net Web Forms (Not MVC) using Master Pages.</p>
  
  <p>Basically I want to do something like this:</p>
  
  <pre><code>&lt;script type="text/javascript"&gt;
      var z = '&lt;%# Request.QueryString["Env"] %&gt;';
  &lt;/script&gt;
  </code></pre>
  
  <p>After I run the code I see:  var z=’’;</p>
  
  <p>I also tried: </p>
  
  <p>var z = '&lt;%= Request.QueryString["Env"] %>';</p>
  
  <p>After I run that code I get the following error so I assume that is not correct:</p>
  
  <p>The Controls collection cannot be modified because the control contains code blocks (i.e. &lt;% ... %>).</p>
  
  <p>I have been doing mainly MVC development these past few years so I am not sure what I am doing wrong.</p>
  
  <p>Please let me know. </p>
  
  <p>Thanks</p>