expo/src/Facebook.js

// @flow

import { NativeModules } from 'react-native';

const { ExponentFacebook } = NativeModules;

type FacebookLoginResult = {
  type: string,
  token?: string,
  expires?: number,
};

type FacebookOptions = {
  permissions?: Array<string>,
  behavior?: 'web' | 'native' | 'browser' | 'system',
};

export default {
  async logInWithReadPermissionsAsync(
    appId: string,
    options?: FacebookOptions
  ): Promise<FacebookLoginResult> {
    if (typeof appId !== 'string') {
      console.warn(
        `logInWithReadPermissionsAsync: parameter 'appId' must be a string, was '${typeof appId}''.`
      );
      appId = String(appId);
    }

    if (!options || typeof options !== 'object') {
      options = {};
    }
    return ExponentFacebook.logInWithReadPermissionsAsync(appId, options);
  },
};