title: Next step after OPTIONS/200OK
body: <p>An Aurelia SPA uses fetch against a different origin server. A preflight OPTIONS request is sent and because the server is configured to respond, the response is 200 OK. </p>
  
  <p>But that's <em>all</em> that happens. </p>
  
  <p>What must I add to make the rest of it happen?</p>
  
  <p>Here's the request.</p>
  
  <pre><code>  this.http.fetch(this.LabelServiceUrl, {
      method: "post",
      mode: "cors",
      headers: {
        "Content-type": "application/json; charset=UTF-8"
      },
      body: json({
        printer: this.LabelPrinter,
        html: html
      })
    }).then(json)
      .then(response =&gt; {
        console.log('Success:', JSON.stringify(response))
      })
      .catch(error =&gt; {
        console.error('Error:', error)
      });
  </code></pre>
  
  <p>IIS is configured by web.config</p>
  
  <pre><code>&lt;system.webServer&gt;
   &lt;httpProtocol&gt;
     &lt;customHeaders&gt;
       &lt;add name="Access-Control-Allow-Origin" value="*" /&gt;
     &lt;/customHeaders&gt;
   &lt;/httpProtocol&gt;
  &lt;/system.webServer&gt;
  </code></pre>