login () {
    const data = {
      username: this.state.username,
      password: this.state.password
    }

    const options = {
      method: 'POST',
      body: JSON.stringify(data),
      headers: {
        'Content-Type': 'application/json',
        credentials: 'include' // tried this too.
        // credentials: 'same-origin'
      }
    }

    fetch('/login', options)
      .then(res => {
        console.log('res', res)
        // cookies.set('connect.sid', document.cookie['connect.sid'])
        console.log(document.cookie['connect.sid'])// undefined
        console.log(res.headers) // empty
        console.log(document.cookies) // undefined
        // cookies.set('connect.sid', res.headers) // need to set this but where is the cookie from server?
      })
      .then(this.clearInputFields.bind(this))
  }

HTTP/1.1 200 OK
x-powered-by: Express
content-type: text/html; charset=utf-8
content-length: 14
etag: W/"e-Xft1SGvF5rPEfqfROtKDA2epBao"
set-cookie: connect.sid=s%3ACRnk3A0b0o5T8VSQTVpvTUgW54lO38IJ.skdIbmipmb1CGn6oEQ5KzdS2zGdNiZQrFDwU5cTuy7A; Path=/
date: Tue, 05 Jun 2018 00:32:15 GMT
connection: close
Vary: Accept-Encoding