title: How to retain a value set in javascript after postback
body: <p>I have the following problem. I have a page and in the <code>Document Ready</code> event I call a web service that returns a string value. After that the value is assigned to a Label control (visible). After that I want to use the value in the Code Behind but I don't know how to get it. </p>
  
  <p>All the events <code>Page_load</code>, <code>Page_Prerender</code>, ... have passed before the value has been retrieved from the service so I can't get it in any of them. </p>
  
  <p>If I try to get it on a button click the page does a postback and loses the value.</p>
  
  <p>I tried to find the control via <code>Request.Form</code> but it still returns nothing.</p>