Jutsu React Native:react Native Components

React Native Components

Use this skill when building user interfaces with React Native's core components and creating custom reusable components.

Key Concepts

Core Components

React Native provides platform-agnostic components that map to native views:

import React from 'react';
import {
  View,
  Text,
  Image,
  ScrollView,
  TextInput,
  TouchableOpacity,
  SafeAreaView,
} from 'react-native';

export default function App() {
  return (
    <SafeAreaView style={{ flex: 1 }}>
      <ScrollView>
        <View>
          <Text>Hello, React Native!</Text>
          <Image
            source={{ uri: 'https://example.com/image.jpg' }}
            style={{ width: 200, height: 200 }}
          />
          <TextInput
            placeholder="Enter text"
            style={{ borderWidth: 1, padding: 10 }}
          />
          <TouchableOpacity => console.log('Pressed')}>
            <Text>Press Me</Text>
          </TouchableOpacity>
        </View>
      </ScrollView>
    </SafeAreaView>
  );
}

View Component

The fundamental building block:

import { View } from 'react-native';

function Container({ children }: { children: React.ReactNode }) {
  return (
    <View style={{
      flex: 1,
      padding: 16,
      backgroundColor: '#fff',
    }}>
      {children}
    </View>
  );
}

Text Component

All text must be wrapped in <Text>:

import { Text } from 'react-native';

function Heading({ children }: { children: string }) {
  return (
    <Text style={{
      fontSize: 24,
      fontWeight: 'bold',
      color: '#333',
    }}>
      {children}
    </Text>
  );
}

function Body({ children }: { children: string }) {
  return (
    <Text style={{
      fontSize: 16,
      lineHeight: 24,
      color: '#666',
    }}>
      {children}
    </Text>
  );
}

Image Component

Display images from various sources:

import { Image } from 'react-native';

// Remote image
<Image
  source={{ uri: 'https://example.com/image.jpg' }}
  style={{ width: 200, height: 200 }}
/>

// Local image
<Image
  source={require('./assets/logo.png')}
  style={{ width: 100, height: 100 }}
/>

// With resize mode
<Image
  source={{ uri: 'https://example.com/image.jpg' }}
  style={{ width: 200, height: 200 }}
  resizeMode="cover"
/>

Best Practices

Use SafeAreaView for iOS Notch

Always use SafeAreaView to handle safe areas:

import { SafeAreaView } from 'react-native';

export default function App() {
  return (
    <SafeAreaView style={{ flex: 1, backgroundColor: '#fff' }}>
      {/* Your content */}
    </SafeAreaView>
  );
}

FlatList for Long Lists

Use FlatList instead of ScrollView for performance:

import { FlatList, Text, View } from 'react-native';

interface Item {
  id: string;
  title: string;
}

function ItemList({ items }: { items: Item[] }) {
  return (
    <FlatList
      data={items}
      keyExtractor={(item) => item.id}
      renderItem={({ item }) => (
        <View style={{ padding: 16 }}>
          <Text>{item.title}</Text>
        </View>
      )}
      // Performance optimizations
      removeClippedSubviews={true}
      maxToRenderPerBatch={10}
      updateCellsBatchingPeriod={50}
      initialNumToRender={10}
      windowSize={10}
    />
  );
}

Touchable Components

Use appropriate touchables for platform:

import { TouchableOpacity, TouchableHighlight, Pressable } from 'react-native';

// Modern approach - Pressable (recommended)
<Pressable
  => console.log('Pressed')}
  style={({ pressed }) => [
    { padding: 12, backgroundColor: pressed ? '#ddd' : '#fff' }
  ]}
>
  {({ pressed }) => (
    <Text style={{ color: pressed ? '#000' : '#333' }}>Press Me</Text>
  )}
</Pressable>

// TouchableOpacity - simple fade effect
<TouchableOpacity
  => console.log('Pressed')}
  activeOpacity={0.7}
>
  <Text>Press Me</Text>
</TouchableOpacity>

Component Composition

Build complex UIs from simple components:

import React from 'react';
import { View, Text, StyleSheet } from 'react-native';

interface CardProps {
  title: string;
  subtitle?: string;
  children?: React.ReactNode;
}

function Card({ title, subtitle, children }: CardProps) {
  return (
    <View style={styles.card}>
      <View style={styles.header}>
        <Text style={styles.title}>{title}</Text>
        {subtitle && <Text style={styles.subtitle}>{subtitle}</Text>}
      </View>
      {children && <View style={styles.content}>{children}</View>}
    </View>
  );
}

const styles = StyleSheet.create({
  card: {
    backgroundColor: '#fff',
    borderRadius: 8,
    padding: 16,
    marginVertical: 8,
    shadowColor: '#000',
    shadowOffset: { width: 0, height: 2 },
    shadowOpacity: 0.1,
    shadowRadius: 4,
    elevation: 3,
  },
  header: {
    marginBottom: 12,
  },
  title: {
    fontSize: 18,
    fontWeight: 'bold',
    color: '#333',
  },
  subtitle: {
    fontSize: 14,
    color: '#666',
    marginTop: 4,
  },
  content: {
    marginTop: 8,
  },
});

export default Card;

Common Patterns

List with Pull-to-Refresh

import React, { useState, useCallback } from 'react';
import { FlatList, RefreshControl, Text, View } from 'react-native';

interface Item {
  id: string;
  title: string;
}

function RefreshableList({ items, onRefresh }: {
  items: Item[];
  onRefresh: () => Promise<void>;
}) {
  const [refreshing, setRefreshing] = useState(false);

  const handleRefresh = useCallback(async () => {
    setRefreshing(true);
    await onRefresh();
    setRefreshing(false);
  }, [onRefresh]);

  return (
    <FlatList
      data={items}
      keyExtractor={(item) => item.id}
      renderItem={({ item }) => (
        <View style={{ padding: 16 }}>
          <Text>{item.title}</Text>
        </View>
      )}
      refreshControl={
        <RefreshControl refreshing={refreshing} />
      }
    />
  );
}

Infinite Scroll List

import React from 'react';
import { FlatList, ActivityIndicator, View } from 'react-native';

interface Item {
  id: string;
  title: string;
}

function InfiniteList({
  items,
  loading,
  onEndReached
}: {
  items: Item[];
  loading: boolean;
  onEndReached: () => void;
}) {
  return (
    <FlatList
      data={items}
      keyExtractor={(item) => item.id}
      renderItem={({ item }) => (
        <View style={{ padding: 16 }}>
          <Text>{item.title}</Text>
        </View>
      )}
     
     
      ListFooterComponent={
        loading ? (
          <View style={{ padding: 16 }}>
            <ActivityIndicator size="large" />
          </View>
        ) : null
      }
    />
  );
}

Modal Component

import React from 'react';
import {
  Modal,
  View,
  Text,
  TouchableOpacity,
  StyleSheet,
} from 'react-native';

interface CustomModalProps {
  visible: boolean;
  title: string;
  children: React.ReactNode;
  onClose: () => void;
}

function CustomModal({ visible, title, children, onClose }: CustomModalProps) {
  return (
    <Modal
      visible={visible}
      animationType="slide"
      transparent={true}
     
    >
      <View style={styles.overlay}>
        <View style={styles.modal}>
          <View style={styles.header}>
            <Text style={styles.title}>{title}</Text>
            <TouchableOpacity
              <Text style={styles.closeButton}>✕</Text>
            </TouchableOpacity>
          </View>
          <View style={styles.content}>{children}</View>
        </View>
      </View>
    </Modal>
  );
}

const styles = StyleSheet.create({
  overlay: {
    flex: 1,
    backgroundColor: 'rgba(0, 0, 0, 0.5)',
    justifyContent: 'center',
    alignItems: 'center',
  },
  modal: {
    width: '80%',
    backgroundColor: '#fff',
    borderRadius: 12,
    padding: 20,
  },
  header: {
    flexDirection: 'row',
    justifyContent: 'space-between',
    alignItems: 'center',
    marginBottom: 16,
  },
  title: {
    fontSize: 20,
    fontWeight: 'bold',
  },
  closeButton: {
    fontSize: 24,
    color: '#666',
  },
  content: {
    marginTop: 8,
  },
});

export default CustomModal;

Form Input Component

import React, { useState } from 'react';
import {
  View,
  TextInput,
  Text,
  StyleSheet,
  TextInputProps,
} from 'react-native';

interface FormInputProps extends TextInputProps {
  label: string;
  error?: string;
}

function FormInput({ label, error, ...props }: FormInputProps) {
  const [isFocused, setIsFocused] = useState(false);

  return (
    <View style={styles.container}>
      <Text style={styles.label}>{label}</Text>
      <TextInput
        {...props}
        style={[
          styles.input,
          isFocused && styles.inputFocused,
          error && styles.inputError,
        ]}
        => setIsFocused(true)}
        => setIsFocused(false)}
      />
      {error && <Text style={styles.error}>{error}</Text>}
    </View>
  );
}

const styles = StyleSheet.create({
  container: {
    marginVertical: 8,
  },
  label: {
    fontSize: 14,
    fontWeight: '600',
    marginBottom: 4,
    color: '#333',
  },
  input: {
    borderWidth: 1,
    borderColor: '#ddd',
    borderRadius: 8,
    padding: 12,
    fontSize: 16,
  },
  inputFocused: {
    borderColor: '#007AFF',
  },
  inputError: {
    borderColor: '#FF3B30',
  },
  error: {
    color: '#FF3B30',
    fontSize: 12,
    marginTop: 4,
  },
});

export default FormInput;

Anti-Patterns

Don't Nest ScrollViews

// Bad - Nested ScrollViews cause issues
<ScrollView>
  <ScrollView>
    <Text>Content</Text>
  </ScrollView>
</ScrollView>

// Good - Use single ScrollView
<ScrollView>
  <View>
    <Text>Content</Text>
  </View>
</ScrollView>

Don't Use Inline Styles for Static Values

// Bad - Creates new object on every render
<View style={{ padding: 16, backgroundColor: '#fff' }}>
  <Text>Content</Text>
</View>

// Good - Use StyleSheet
const styles = StyleSheet.create({
  container: {
    padding: 16,
    backgroundColor: '#fff',
  },
});

<View style={styles.container}>
  <Text>Content</Text>
</View>

Don't Forget to Set keyExtractor

// Bad - May cause rendering issues
<FlatList
  data={items}
  renderItem={({ item }) => <Text>{item.title}</Text>}
/>

// Good - Provide unique key
<FlatList
  data={items}
  keyExtractor={(item) => item.id}
  renderItem={({ item }) => <Text>{item.title}</Text>}
/>

Don't Use Index as Key

// Bad - Index as key causes issues with reordering
<FlatList
  data={items}
  keyExtractor={(item, index) => index.toString()}
  renderItem={({ item }) => <Text>{item.title}</Text>}
/>

// Good - Use unique identifier
<FlatList
  data={items}
  keyExtractor={(item) => item.id}
  renderItem={({ item }) => <Text>{item.title}</Text>}
/>

Related Skills

• react-native-styling: Styling components with StyleSheet
• react-native-navigation: Navigation between screens
• react-native-performance: Optimizing component performance