title: No 'Access-Control-Allow-Origin in reactJS
body: <p>I want to know how set Access-Control-Allow-Origin in axios post method at reactJS or react-native environment?
  I use CORS Add-ons and it works but I want to set it in the header too, I try these ways but none of them does not work.</p>
  
  <pre><code>axios.defaults.headers.post['Access-Control-Allow-Origin'] = '*';
  </code></pre>
  
  <p>and</p>
  
  <pre><code>let axiosConfig = {
    headers: {
      'method':'POST',
      'X-Requested-With': 'XMLHttpRequest',
      'Content-Type': 'application/x-www-form-urlencoded',
      'Access-Control-Allow-Origin': '*',
    }
  };
  </code></pre>