title: Force Content-Type to application/json with mode no-cors
body: <p>i want to force the content-type to application/json but i have a mode "no-cors" and actually the return for content-type is : text/plain;charset=UTF-8 its the same when i pass the headers so i don't know how do this.</p>
  
  <p>I have already tried to use fetch or Axios, the URL is in HTTP and i work in local so maybe it's the problem?
  I have tried on Postman, that work great.</p>
  
  <pre><code>     fetch('http://link', {
              method: 'POST',
              credentials: 'include',
              redirect: 'follow',
              mode: 'no-cors',
              headers: {
                  'Accept': 'application/json',
                  'Content-Type': 'application/json'
              },
              body: JSON.stringify({
                  "cluster_id" : [],
                  "surname" :["albert"],
                  "gender" :[],
  
              }),
          }).then((result) =&gt; {
              this.setState({ allClient: result.data }, () =&gt; {
                  this.setState({ load: true })
                  console.log(this.state.allClient)
          })
  
  </code></pre>
  
  <p>So, i want to have content type: application/json and not Content-Type: text/plain;charset=UTF-8</p>