Enable developer console in browser and navigate to:
Look for the response of POST request in the network tab of developer console: https://www.facebook.com/v2.6/dialog/oauth/confirm?dpr=1 it contains the access token parameter. Just search for 'access_token' in the response. For the lazy people (like myself) i made a small helper that parses the token from response https://taseppa.github.io/tokenparser.github.io/
how to collect token?