react native: how to know th softkey height

import { Dimensions , StatusBar } from 'react-native';

const screenHeight = Dimensions.get('screen').height;
const windowHeight = Dimensions.get('window').height;
const navbarHeight = screenHeight - windowHeight + StatusBar.currentHeight;
import {Dimensions, StatusBar} from 'react-native'; 

const DEVICE_HEIGHT = Dimensions.get('screen').height;
const STATUS_BAR = StatusBar.statusBarHeight || 24; 
const WINDOW_HEIGHT = Dimensions.get('window').height;