Unable to display React Native Expo custom component

Question

I'm a newbie and can't figure out why one of my custom components shows up but the other doesn't.

Home screen:

import React from 'react';
import {View, Text} from 'react-native';
import { SafeAreaView } from 'react-native-safe-area-context';
import { ScrollView, TouchableOpacity } from 'react-native-gesture-handler';
import { DrawerActions } from '@react-navigation/native';
import Ionicons from '@expo/vector-icons/Ionicons';

import { useGrid } from '../context/gridProvider'; // Context provider

import Exam from '../components/Exam';
import Clock from '../components/clock';

const Home = ({navigation}) => {

    const {checkedItems, setCheckedItmes} = useGrid()
    
    return (
      <SafeAreaView style={{flex:1}}>
        <ScrollView style={{padding:20}}>
          <View style={{flexDirection: 'row', justifyContent: 'space-between', marginBottom:20,}}>
          <Text style={{fontSize: 16, fontWeight: 700}}></Text>
            <Text style={{fontSize: 32, fontWeight: 700, color:'#444'}}>Today’s exam</Text>
            <TouchableOpacity onPress={() => navigation.dispatch(DrawerActions.openDrawer())}>
              <Ionicons name="menu" size={32} color="#333" />
            </TouchableOpacity>
          </View>
          <Clock /> // The clock is displayed
          <Exam /> // The exam list is not displayed
        </ScrollView>
      </SafeAreaView>
    )
  }

  export default Home

The clock is displayed, but the exam is not.

Examination components:

import React from 'react';
import {View, Text, StyleSheet} from 'react-native';
import { useGrid } from '../context/gridProvider';
import examData from '../data/trialData';

const Exam = () => {
  
  const {checkedItems, setCheckedItmes} = useGrid();

    checkedItems.forEach((key) => {

        console.log(examData[key-1].title);
        
        return(

          <View style={{flex:1, alignItems: 'center', marginTop: 100, flexDirection: 'row'}}>
              <Text style={{color: '#333'}}>{examData[key-1].title}</Text>
              <Text>{examData[key-1].startTime}</Text>
              <Text>{examData[key-1].endTime}</Text>
          </View>

        )
    });
}

export default Exam

(Note: my first object ID is 1, not zero, so subtract 1 from the key value)

I use context to handle global availability to determine which exams are selected from a list on another screen.

When you select an exam from the list, the console.log(examData[key-1].title); statement does output the correct information to the terminal, except for the clock. Otherwise, nothing is displayed in the app.

I tried removing the clock component to prevent it from pushing the list off the page.

Does anyone know what I did wrong...

Answer 1

The function Exam always returns undefined because forEach returns undefined.

Solution: Use map instead of forEach.

import React from 'react';
import {View, Text, StyleSheet} from 'react-native';
import { useGrid } from '../context/gridProvider';
import examData from '../data/trialData';

const Exam = () => {
  
  const {checkedItems, setCheckedItmes} = useGrid();

    checkedItems.map((key) => {

        console.log(examData[key-1].title);
        
        return(

          <View style={{flex:1, alignItems: 'center', marginTop: 100, flexDirection: 'row'}}>
              <Text style={{color: '#333'}}>{examData[key-1].title}</Text>
              <Text>{examData[key-1].startTime}</Text>
              <Text>{examData[key-1].endTime}</Text> 
          </View>  

        )
    });
}

export default Exam