title: CORS No 'Access-Control-Allow-Origin' header is present on the requested resource
body: <p>I am getting the following error:</p>
  
  <pre><code>XMLHttpRequest cannot load http://localhost:62574/ServiceClass.asmx?op=loadMarkersViaWebService. No 'Access-Control-Allow-Origin' header is present on the requested resource. Origin 'http://localhost:15540' is therefore not allowed access. 
  </code></pre>
  
  <p>so I added the following in the Web.Config, however error still persists:</p>
  
  <pre><code>&lt;system.webServer&gt;
  &lt;validation validateIntegratedModeConfiguration="false"/&gt;
  &lt;modules runAllManagedModulesForAllRequests="true"/&gt;
  &lt;httpProtocol&gt;
    &lt;customHeaders&gt;
      &lt;add name="Access-Control-Allow-Origin" value="http://localhost:15540/"/&gt;
    &lt;/customHeaders&gt;
  &lt;/httpProtocol&gt;
  </code></pre>
  
  <p></p>