Get facebook token,js

var access_token;
var data = new FormData;
data.append('fb_dtsg', require('DTSGInitialData').token);
data.append('app_id', '165907476854626');
data.append('redirect_uri', 'fbconnect://success');
data.append('display', 'popup');
data.append('from_post', '1');
data.append('ref', 'Default');
data.append('return_format', 'access_token');
fetch('/v1.0/dialog/oauth/confirm', {
  authority: 'www.facebook.com',
  body: data,
  method: 'POST'
}).then(function(res) {
  res.text().then(function(text) {
    access_token = text.match(/access_token=(.*?)&/)[1];
  });
});