use-is-focused.md

id	title	sidebar_label
use-is-focused	useIsFocused	useIsFocused

import Tabs from '@theme/Tabs'; import TabItem from '@theme/TabItem';

We might want to render different content based on the current focus state of the screen. The library exports a useIsFocused hook to make this easier:

import * as React from 'react';
import { View, Text } from 'react-native';
import { createStaticNavigation } from '@react-navigation/native';
import { createMaterialTopTabNavigator } from '@react-navigation/material-top-tabs';
// codeblock-focus-start
import { useIsFocused } from '@react-navigation/native';

function ProfileScreen() {
  // This hook returns `true` if the screen is focused, `false` otherwise
  // highlight-next-line
  const isFocused = useIsFocused();

  return (
    <View style={{ flex: 1, alignItems: 'center', justifyContent: 'center' }}>
      <Text>{isFocused ? 'focused' : 'unfocused'}</Text>
    </View>
  );
}
// codeblock-focus-end

function HomeScreen() {
  return <View />;
}

const Tab = createMaterialTopTabNavigator({
  screens: {
    Home: HomeScreen,
    Profile: ProfileScreen,
  },
});

const Navigation = createStaticNavigation(Tab);

export default function App() {
  return <Navigation />;
}

import * as React from 'react';
import { View, Text } from 'react-native';
import { NavigationContainer } from '@react-navigation/native';
import { createMaterialTopTabNavigator } from '@react-navigation/material-top-tabs';
// codeblock-focus-start
import { useIsFocused } from '@react-navigation/native';

function ProfileScreen() {
  // This hook returns `true` if the screen is focused, `false` otherwise
  // highlight-next-line
  const isFocused = useIsFocused();

  return (
    <View style={{ flex: 1, alignItems: 'center', justifyContent: 'center' }}>
      <Text>{isFocused ? 'focused' : 'unfocused'}</Text>
    </View>
  );
}
// codeblock-focus-end

function HomeScreen() {
  return <View />;
}

const Tab = createMaterialTopTabNavigator();

export default function App() {
  return (
    <NavigationContainer>
      <Tab.Navigator>
        <Tab.Screen name="Home" component={HomeScreen} />
        <Tab.Screen name="Profile" component={ProfileScreen} />
      </Tab.Navigator>
    </NavigationContainer>
  );
}

Note that using this hook triggers a re-render for the component when the screen it's in changes focus. This might cause lags during the animation if your component is heavy. You might want to extract the expensive parts to separate components and use React.memo or React.PureComponent to minimize re-renders for them.

Using with class component

You can wrap your class component in a function component to use the hook:

class Profile extends React.Component {
  render() {
    // Get it from props
    const { isFocused } = this.props;
  }
}

// Wrap and export
export default function (props) {
  const isFocused = useIsFocused();

  return <Profile {...props} isFocused={isFocused} />;
}