ScrollView component in React Native - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to import the ScrollView component from React Native.

React Native

import { [1] } from 'react-native';

Drag options to blanks, or click blank then click option'

AText

BScrollView

CView

DButton

Attempts:

3 left

💡 Hint

Common Mistakes

Importing View instead of ScrollView.

Forgetting to import ScrollView.

The ScrollView component must be imported from 'react-native' to use it in your app.

2fill in blank

medium

Complete the code to wrap content inside a ScrollView component.

React Native

return (
  <[1]>
    <Text>Scrollable content</Text>
  </[1]>
);

Drag options to blanks, or click blank then click option'

AScrollView

BFlatList

CSafeAreaView

DView

Attempts:

3 left

💡 Hint

Common Mistakes

Using View which does not scroll.

Using FlatList which is for lists, not simple scroll.

Wrapping content inside ScrollView makes it scrollable vertically by default.

3fill in blank

hard

Fix the error in the ScrollView usage by completing the missing prop to enable horizontal scrolling.

React Native

<ScrollView [1]>
  <Text>Swipe horizontally</Text>
</ScrollView>

Drag options to blanks, or click blank then click option'

Avertical={true}

BpagingEnabled={false}

CscrollEnabled={false}

Dhorizontal={true}

Attempts:

3 left

💡 Hint

Common Mistakes

Using vertical prop which does not exist.

Disabling scroll with scrollEnabled={false}.

Setting horizontal={true} makes the ScrollView scroll horizontally instead of vertically.

4fill in blank

hard

Fill both blanks to create a ScrollView with a fixed height and enable vertical scrolling.

React Native

const styles = StyleSheet.create({
  container: {
    height: [1],
    backgroundColor: 'lightgray'
  }
});

return (
  <ScrollView style={styles.container} [2]>
    <Text>Lots of content here</Text>
  </ScrollView>
);

Drag options to blanks, or click blank then click option'

A300

Bhorizontal={true}

CscrollEnabled={true}

Dflex: 1

Attempts:

3 left

💡 Hint

Common Mistakes

Using flex: 1 for height which fills all space instead of fixed height.

Setting horizontal={true} when vertical scroll is needed.

Setting a fixed height like 300 limits the ScrollView's visible area. The prop scrollEnabled={true} ensures scrolling is active.

5fill in blank

hard

Fill all three blanks to create a ScrollView that scrolls horizontally, hides the scroll indicator, and snaps to page.

React Native

<ScrollView [1] [2] [3]>
  <View style={{width: 300, height: 200, backgroundColor: 'red'}} />
  <View style={{width: 300, height: 200, backgroundColor: 'blue'}} />
</ScrollView>

Drag options to blanks, or click blank then click option'

Ahorizontal={true}

BshowsHorizontalScrollIndicator={false}

CpagingEnabled={true}

DscrollEnabled={false}

Attempts:

3 left

💡 Hint

Common Mistakes

Disabling scroll with scrollEnabled={false}.

Not hiding the scroll indicator when asked.

To create a horizontal scroll that snaps pages and hides the scroll bar, use horizontal={true}, showsHorizontalScrollIndicator={false}, and pagingEnabled={true}.

Practice

1. What is the main purpose of the ScrollView component in React Native?

easy

A. To manage app navigation between screens

B. To allow users to scroll content that is larger than the screen

C. To display images only

D. To create buttons for user interaction

Solution

1. Step 1: Understand ScrollView's role

   The ScrollView component is designed to let users scroll through content that does not fit on the screen.

2. Step 2: Compare options

   Options A, B, and C describe other components or features, not ScrollView.

3. Final Answer:

   To allow users to scroll content that is larger than the screen -> Option B

4. Quick Check:

   ScrollView = scrolls content [OK]

Hint: ScrollView scrolls content bigger than screen [OK]

Common Mistakes:

• Confusing ScrollView with navigation components
• Thinking ScrollView only displays images
• Assuming ScrollView creates buttons

2. Which of the following is the correct way to make a ScrollView scroll horizontally?

easy

A. ...

B. ...

C. ...

D. ...

Solution

1. Step 1: Recall ScrollView horizontal prop

   ScrollView uses the horizontal boolean prop to enable horizontal scrolling.

2. Step 2: Check syntax correctness

   Only ... uses the correct prop name and value syntax. Others use invalid or non-existent props.

3. Final Answer:

   <ScrollView horizontal={true}>...</ScrollView> -> Option C

4. Quick Check:

   horizontal={true} enables horizontal scroll [OK]

Hint: Use horizontal={true} prop for horizontal scroll [OK]

Common Mistakes:

• Using wrong prop names like scrollDirection or direction
• Forgetting to set horizontal to true
• Using shorthand props incorrectly

3. What will be the visible behavior of this code snippet?

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

export default function App() {
  return (
    
      {[...Array(20)].map((_, i) => (
        Item {i + 1}
      ))}
    
  );
}

medium

A. A vertical list of 20 text items that can be scrolled up and down

B. A horizontal list of 20 text items that can be scrolled left and right

C. Only the first 5 items are visible, no scrolling possible

D. App will crash due to missing keys in list items

Solution

1. Step 1: Analyze ScrollView default behavior

   ScrollView scrolls vertically by default, so the list will scroll up and down.

2. Step 2: Check list rendering and keys

   The code uses keys correctly with key={i} and renders 20 Text items inside ScrollView.

3. Final Answer:

   A vertical list of 20 text items that can be scrolled up and down -> Option A

4. Quick Check:

   ScrollView default = vertical scroll [OK]

Hint: ScrollView scrolls vertically by default [OK]

Common Mistakes:

• Assuming horizontal scroll without horizontal prop
• Thinking keys are missing causing crash
• Believing only a few items show without scroll

4. Identify the error in this ScrollView usage:

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

export default function App() {
  return (
    
      Item 1
      Item 2
    
  );
}

medium

A. Missing key props on Text components

B. Text components cannot be children of ScrollView

C. ScrollView requires a style prop to work

D. The horizontal prop should be a boolean, not a string

Solution

1. Step 1: Check horizontal prop type

   The horizontal prop expects a boolean value, but "true" is a string here, which is incorrect.

2. Step 2: Verify other props and children

   Text components are valid children, style is optional, and keys are not required for static children.

3. Final Answer:

   The horizontal prop should be a boolean, not a string -> Option D

4. Quick Check:

   horizontal must be boolean, not string [OK]

Hint: Pass boolean true, not string "true" for horizontal [OK]

Common Mistakes:

• Using string "true" instead of boolean true
• Thinking keys are needed for static children
• Assuming style prop is mandatory

5. You want to display a list of 50 images horizontally scrollable inside a ScrollView. Which approach is best to ensure good performance and user experience?

hard

A. Use FlatList horizontal={true} to render images lazily

B. Use ScrollView without horizontal prop and render images vertically

C. Use ScrollView horizontal={true} with all 50 images rendered inside

D. Use View with manual scrolling logic

Solution

1. Step 1: Understand ScrollView limits

   ScrollView renders all children at once, which can hurt performance with many items like 50 images.

2. Step 2: Choose better component for large lists

   FlatList supports lazy loading and virtualization, improving performance for large lists and supports horizontal scrolling.

3. Step 3: Evaluate other options

   Use ScrollView without horizontal prop and render images vertically scrolls vertically, not horizontal as required. Use View with manual scrolling logic requires complex manual logic and is not recommended.

4. Final Answer:

   Use <FlatList horizontal={true}> to render images lazily -> Option A

5. Quick Check:

   FlatList = best for large scrollable lists [OK]

Hint: Use FlatList for large scrollable lists, not ScrollView [OK]

Common Mistakes:

• Using ScrollView for large lists causing slow performance
• Ignoring horizontal prop for horizontal scroll
• Trying manual scroll logic instead of built-in components