formFileUpload.js

export function fileUpload(file) {
  let formData = new FormData();

  for(name in file) {
    formData.append(name, file[name]);
  }

  return fetch('https://my-website.com/api/file/upload', {
      method: 'POST',
      // if your app is storing auth tokens in a cookie include credentials
      // credentials: 'include',
      body: formData
    })
      .then(response => 
        response.json().then(json => ({
          status: response.status,
          statusText: response.statusText,
          json
        })
      ))
      .then(
        ({ status, statusText, json }) => {
          if (status >= 400) {
            // API returned a crappy response
            console.log('error:', status, statusText, json);
          } else {
            // Upload done!
            return json;
          }
        },
      )
      .catch(err => console.log(err));
  };
}