title: React-Native fetch through proxy
body: <p>How can I set options in the <code>fetch</code> method of react-native to make a call to a webserver go through a proxy.</p>
  
  <p>Currently I am using <a href="https://github.com/mzabriskie/axios" rel="noreferrer">axios</a> but this doesn't work. </p>
  
  <p>After adding a host header to the fetch, I can make a request through charles-proxy but it doesn't work with squid. (<code>Error: invalid url</code>).</p>