Auth0 - Create new passwordless user and link him to current account on first login

create_and_link_users.js

function (user, context, callback) {
  var request = require('request@2.56.0');

  // Create and link user only during first login
  if (context.stats.loginsCount > 1) {
    return callback(null, user, context);
  }
 
  // Create new user
  // Note: the access token must have create:users and update:users scopes
  request.post({
    url: auth0.baseUrl + '/users',
    headers: {
     Authorization: 'Bearer ' + configuration.ACCESS_TOKEN
    },
    json: { connection: 'email', email: user.email }
  },
  function(err, response, body) {
    
    if (err) return callback(err);
    if (response.statusCode !== 201) return callback(new Error(body));
    
    var newUserId = body.user_id.split('|')[1];

    // Link the accounts. Primary acct: original user. Secondary acct: newly created user.
    request.post({ 
      url: auth0.baseUrl + '/users/' + user.user_id + '/identities',
      headers: {
        Authorization: 'Bearer ' + configuration.ACCESS_TOKEN
      },
      json: {provider: 'email', user_id: newUserId}
    },
    function(err, response, body) {
      if (err) return callback(err);
      if (response.statusCode >= 400) return callback(new Error('Error linking accounts: ' + response.statusMessage));
      
      return callback(null, user, context);
    });
  });
  
}