React Native, passing data between screens when using BottomTabsNavigator

I am trying to make a react native application. I am using Bottom Tab Navigation, and I have 2 screens. On the first screen, a qr code is first scanned, it contains a string, which is written on the screen.

Then I would like to write out the afformentioned string on the second tab.

How can I pass this data between the screens of the Bottom Tab Navigator?

App:

import { StatusBar } from 'expo-status-bar';
import { StyleSheet, Text, View } from 'react-native';
import React from 'react';
import { NavigationContainer } from '@react-navigation/native';
import { createBottomTabNavigator } from '@react-navigation/bottom-tabs';
import QrcodeScreen from './src/screens/QrcodeScreen';
import EttermekScreen from './src/screens/EttermekScreen';

const Tab =createBottomTabNavigator();

export default function App() {
  return (
    <NavigationContainer>
      <Tab.Navigator>
        <Tab.Screen name='Qrcode' component={QrcodeScreen} />
        <Tab.Screen name='Ettermek' component={EttermekScreen} />
      </Tab.Navigator>
    </NavigationContainer>
  );
}

const styles = StyleSheet.create({
  container: {
    flex: 1,
    backgroundColor: '#fff',
    alignItems: 'center',
    justifyContent: 'center',
  },
});

QrcodeScreen:

import { StatusBar } from 'expo-status-bar';
import React, { useState, useEffect } from 'react';
import { Text, View, StyleSheet, Button } from 'react-native';
import { BarCodeScanner } from 'expo-barcode-scanner';


export default function QrcodeScreen() {
    const [hasPermission, setHasPermission] = useState(null);
    const [scanned, setScanned] = useState(false);
    const [text, setText] = useState('Not yet scanned')
  
    const askForCameraPermission = () => {
      (async () => {
        const { status } = await BarCodeScanner.requestPermissionsAsync();
        setHasPermission(status === 'granted');
      })()
    }
  
    // Request Camera Permission
    useEffect(() => {
      askForCameraPermission();
    }, []);
  
    // What happens when we scan the bar code
    const handleBarCodeScanned = ({ type, data }) => {
      setScanned(true);
      setText(data)
      console.log('Type: ' + type + '\nData: ' + data)
    };
  
    // Check permissions and return the screens
    if (hasPermission === null) {
      return (
        <View style={styles.container}>
          <Text>Requesting for camera permission</Text>
        </View>)
    }
    if (hasPermission === false) {
      return (
        <View style={styles.container}>
          <Text style={{ margin: 10 }}>No access to camera</Text>
          <Button title={'Allow Camera'} onPress={() => askForCameraPermission()} />
        </View>)
    }
  
    // Return the View
    return (
      <View style={styles.container}>
        <View style={styles.barcodebox}>
          <BarCodeScanner
            onBarCodeScanned={scanned ? undefined : handleBarCodeScanned}
            style={{ height: 400, width: 400 }} />
        </View>
        <Text style={styles.maintext}>{text}</Text>
  
        {scanned && <Button title={'Scan again?'} onPress={() => setScanned(false)} color='tomato' />}
      </View>
    );
  }
  
  const styles = StyleSheet.create({
    container: {
      flex: 1,
      backgroundColor: '#fff',
      alignItems: 'center',
      justifyContent: 'center',
    },
    maintext: {
      fontSize: 16,
      margin: 20,
    },
    barcodebox: {
      alignItems: 'center',
      justifyContent: 'center',
      height: 300,
      width: 300,
      overflow: 'hidden',
      borderRadius: 30,
      backgroundColor: 'tomato'
    }
  });

The screen I would like to print the string:

import { StyleSheet, Text, View } from 'react-native';
import React from 'react';
import { StatusBar } from 'expo-status-bar';
import QrcodeScreen from './QrcodeScreen';

export default function EttermekScreen({ route }) {
  
    const { varisId } = route.params
  
    return (
    <View style={styles.container}>
      <Text>ÉTTERMEK</Text>
      <StatusBar style="auto" />
    </View>
  );
}

const styles = StyleSheet.create({
  container: {
    flex: 1,
    backgroundColor: '#fff',
    alignItems: 'center',
    justifyContent: 'center',
  },
});

>Solution :

In EttermekScreen, you already have this line, const { varisId } = route.params, and grabbing from the props route, so you should be good with it.

Assuming you wanna send data in handleBarCodeScanned to EttermekScreen as a parameter called varisId, you could do it this way:

import { StatusBar } from 'expo-status-bar';
import React, { useState, useEffect } from 'react';
import { Text, View, StyleSheet, Button } from 'react-native';
import { BarCodeScanner } from 'expo-barcode-scanner';


export default function QrcodeScreen({navigation}) {
    const [hasPermission, setHasPermission] = useState(null);
    const [scanned, setScanned] = useState(false);
    const [text, setText] = useState('Not yet scanned')
  
    const askForCameraPermission = () => {
      (async () => {
        const { status } = await BarCodeScanner.requestPermissionsAsync();
        setHasPermission(status === 'granted');
      })()
    }
  
    // Request Camera Permission
    useEffect(() => {
      askForCameraPermission();
    }, []);
  
    // What happens when we scan the bar code
    const handleBarCodeScanned = ({ type, data }) => {
      setScanned(true);
      setText(data)
      console.log('Type: ' + type + '\nData: ' + data)
      navigation.navigate('Ettermek', {
            varisId: data
          });
    };
  
    // Check permissions and return the screens
    if (hasPermission === null) {
      return (
        <View style={styles.container}>
          <Text>Requesting for camera permission</Text>
        </View>)
    }
    if (hasPermission === false) {
      return (
        <View style={styles.container}>
          <Text style={{ margin: 10 }}>No access to camera</Text>
          <Button title={'Allow Camera'} onPress={() => askForCameraPermission()} />
        </View>)
    }
  
    // Return the View
    return (
      <View style={styles.container}>
        <View style={styles.barcodebox}>
          <BarCodeScanner
            onBarCodeScanned={scanned ? undefined : handleBarCodeScanned}
            style={{ height: 400, width: 400 }} />
        </View>
        <Text style={styles.maintext}>{text}</Text>
  
        {scanned && <Button title={'Scan again?'} onPress={() => setScanned(false)} color='tomato' />}
      </View>
    );
  }
  
  const styles = StyleSheet.create({
    container: {
      flex: 1,
      backgroundColor: '#fff',
      alignItems: 'center',
      justifyContent: 'center',
    },
    maintext: {
      fontSize: 16,
      margin: 20,
    },
    barcodebox: {
      alignItems: 'center',
      justifyContent: 'center',
      height: 300,
      width: 300,
      overflow: 'hidden',
      borderRadius: 30,
      backgroundColor: 'tomato'
    }
  });