title: Why is the response body empty (0 bytes on network tab) for this request? Is it to do with this being an extension?
body: <p>When I use the fetch API (Or xmlhttprequest) I get a 0 byte response. Here is a sample of my code:</p>
  
  <pre><code>    fetch("https://myurl", {
        method: "POST",
        headers: {
          'Accept': 'application/json',
          'Content-Type': 'application/json'
        },
        body: JSON.stringify({content: content})
        }).then(function(res){  return res.text()}).then(function(res){ return cb(res);});
  </code></pre>
  
  <p>In the network tab, and in the console.log(res) in the callback, the response is empty. I should note that the response is including a CORS response specifying my chrome extension (which is making the request)</p>
  
  <pre><code>Access-Control-Allow-Origin: chrome-extension://asdjkljuewyrjkhighqwend
  </code></pre>
  
  <p>When I use the requests library (python) and make the same request (copying and pasting the body of the request) I get a valid json response.</p>
  
  <pre><code>resp = requests.post("https://myurl", json=data)
  resp.json() -&gt;&gt; {content}
  </code></pre>
  
  <p>Additionally, when I inspect the server after the Fetch requests, I can see that it happily responded with the json to the request, but something on the browser seems to be blocking it from getting through.</p>