Using an authorization header with Fetch in React Native

Example fetch with authorization header:

fetch('URL_GOES_HERE', { 
    method: 'post', 
    headers: new Headers({
        'Authorization': 'Basic '+btoa('username:password'), 
        'Content-Type': 'application/x-www-form-urlencoded'
    }), 
    body: 'A=1&B=2'
});

It turns out I was using the fetch method incorrectly.

fetch accepts two parameters: an endpoint to the API, and an optional object which can contain body and headers.

I was wrapping the intended object within a second object, which did not get me any desired result.

Here's how it looks on a high level:

    fetch('API_ENDPOINT', options)  
      .then(function(res) {
        return res.json();
       })
      .then(function(resJson) {
        return resJson;
       })

I structured my options object as follows:

    var options = {  
      method: 'POST',
      headers: {
        'Accept': 'application/json',
        'Content-Type': 'application/json',
        'Origin': '',
        'Host': 'api.producthunt.com'
      },
      body: JSON.stringify({
        'client_id': '(API KEY)',
        'client_secret': '(API SECRET)',
        'grant_type': 'client_credentials'
      })
    }