title: express app.get(' /* ') and api CORs issue
body: <p>can you tell me how I can get my json api? </p>
  
  <p>server.js</p>
  
  <pre><code>app.get('/*', function(req, res) {
      res.sendFile(path.join(__dirname, 'public', 'index.html'));
  })
  
  app.get('/api', function(req, res) {
      res.header()
  res.json({'message' : 'hi this is my json obj'});
  })
  </code></pre>
  
  <p>App.js </p>
  
  <pre><code>class App extends React.Component {
      componentDidMount() {
      // let foo;
      axios.get('http://localhost:3000/api')
          .then(res =&gt; {
          console.log(res.data);
          res.data.message;
      })
      .catch(err =&gt; {
          console.log(err);
      })
    }
  </code></pre>
  
  <p>For some reason, like that I can get react router to access localhost:3000/dashboard just fine by inputing the url field. It is keep returning html string. what can i change to make it so that I can receive json object instead of html string?</p>