Fetch - respond to preflight response

I am struggling with fetch over CORS, with authorization:

const token = 'this.is.secret!';
fetch('http://corsserver/api/hello', {
    method: 'get',
    credentials: 'include',
    mode: 'cors',
    headers: {
        'Authorization': `Bearer ${token}`,
        'Content-Type': 'application/x-www-form-urlencoded'
    }
}).then(response => {
  console.log(response);
}).catch(error => {
  console.log(error);
});

When I run this request, Chrome sets the header as:

Request Method:OPTIONS

I look this up and it's a preflighted request.

I mean, that's really cool and stuff. However I can't figure out how to send the actual request after the preflight comes back okay! What's the next step? How do I send the GET request?

I'm missing something very basic here.