expo/src/ScreenOrientation.js

The Expo SDK

// @flow

import { NativeModules } from 'react-native';

export const Orientation = {
  ALL: 'ALL',
  ALL_BUT_UPSIDE_DOWN: 'ALL_BUT_UPSIDE_DOWN',
  PORTRAIT: 'PORTRAIT',
  PORTRAIT_UP: 'PORTRAIT_UP',
  PORTRAIT_DOWN: 'PORTRAIT_DOWN',
  LANDSCAPE: 'LANDSCAPE',
  LANDSCAPE_LEFT: 'LANDSCAPE_LEFT',
  LANDSCAPE_RIGHT: 'LANDSCAPE_RIGHT',
};

type OrientationT = $Enum<typeof Orientation>;

export function allow(orientation: OrientationT) {
  NativeModules.ExponentScreenOrientation.allow(orientation);
}