SectionList for grouped data in React Native - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

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

React Native

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

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

AView

BSectionList

CFlatList

DScrollView

Attempts:

3 left

💡 Hint

Common Mistakes

Importing FlatList instead of SectionList

Forgetting to import SectionList

The SectionList component is used to render grouped lists in React Native.

2fill in blank

medium

Complete the code to define the sections prop with grouped data for SectionList.

React Native

const sections = [
  { title: 'Fruits', data: ['Apple', 'Banana'] },
  { title: 'Vegetables', data: ['Carrot', 'Peas'] }
];

<SectionList
  sections=[1]
  renderItem={({ item }) => <Text>{item}</Text>}
  renderSectionHeader={({ section }) => <Text>{section.title}</Text>}
/>

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

Aitems

Bdata

Csections

Dlist

Attempts:

3 left

💡 Hint

Common Mistakes

Passing 'data' instead of 'sections'

Passing the wrong variable name

The sections prop expects an array of objects each with a title and data array.

3fill in blank

hard

Fix the error in the keyExtractor prop to uniquely identify each item.

React Native

<SectionList
  sections={sections}
  renderItem={({ item }) => <Text>{item}</Text>}
  keyExtractor={(item, index) => item[1]index}
/>

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

A/

B-

C*

D+

Attempts:

3 left

💡 Hint

Common Mistakes

Using arithmetic operators other than '+'

Not returning a string key

The keyExtractor should return a unique string. Concatenating the item with the index using '+' creates a unique key.

4fill in blank

hard

Fill both blanks to correctly render section headers with styling.

React Native

<SectionList
  sections={sections}
  renderItem={({ item }) => <Text>{item}</Text>}
  renderSectionHeader={({ section }) => <Text style={{ [1]: 20, [2]: 'bold' }}>{section.title}</Text>}
/>

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

AfontSize

Bcolor

CfontWeight

Dmargin

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'color' instead of 'fontWeight'

Using 'margin' instead of 'fontSize'

The style uses fontSize to set text size and fontWeight to make text bold.

5fill in blank

hard

Fill all three blanks to complete the SectionList with sticky headers and a key extractor.

React Native

<SectionList
  sections={sections}
  stickySectionHeadersEnabled=[1]
  keyExtractor={(item, index) => item + index.toString()}
  renderItem={({ item }) => <Text>{item}</Text>}
  renderSectionHeader={({ section }) => <Text style={{ fontWeight: [2], fontSize: [3] }}>{section.title}</Text>}
/>

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

Atrue

B'bold'

C18

Dfalse

Attempts:

3 left

💡 Hint

Common Mistakes

Using false for stickySectionHeadersEnabled

Using numeric fontWeight

Using string for fontSize

Sticky headers are enabled by setting stickySectionHeadersEnabled to true. The header text is bold with fontWeight 'bold' and fontSize 18.

Practice

1. What is the main purpose of using SectionList in React Native?

easy

A. To display a list of items grouped by sections with headers

B. To create a grid layout of images

C. To handle user input forms

D. To navigate between screens

Solution

1. Step 1: Understand SectionList usage

   SectionList is designed to show lists grouped by sections, each with a header and items.

2. Step 2: Compare options with SectionList purpose

   Options B, C, and D describe other UI or functionality unrelated to grouped lists.

3. Final Answer:

   To display a list of items grouped by sections with headers -> Option A

4. Quick Check:

   SectionList = grouped list display [OK]

Hint: SectionList groups items with headers, unlike FlatList [OK]

Common Mistakes:

• Confusing SectionList with FlatList
• Thinking SectionList is for navigation
• Assuming SectionList creates grids

2. Which of the following is the correct way to define the sections prop for a SectionList?

easy

A. [{ title: 'Fruits', data: ['Apple', 'Banana'] }, { title: 'Veggies', data: ['Carrot'] }]

B. ['Fruits', 'Apple', 'Banana', 'Veggies', 'Carrot']

C. { title: 'Fruits', items: ['Apple', 'Banana'] }

D. [{ header: 'Fruits', items: ['Apple', 'Banana'] }]

Solution

1. Step 1: Recall SectionList sections structure

   Each section is an object with a title and a data array of items.

2. Step 2: Check options for correct keys and structure

   [{ title: 'Fruits', data: ['Apple', 'Banana'] }, { title: 'Veggies', data: ['Carrot'] }] matches the required format. Options B, C, and D use wrong keys or structure.

3. Final Answer:

   [{ title: 'Fruits', data: ['Apple', 'Banana'] }, { title: 'Veggies', data: ['Carrot'] }] -> Option A

4. Quick Check:

   sections = array of {title, data} objects [OK]

Hint: Sections need title and data keys exactly [OK]

Common Mistakes:

• Using wrong keys like 'items' or 'header'
• Passing a flat array instead of array of objects
• Confusing data array with section title

3. Given this code snippet, what will be displayed as section headers?

const sections = [
  { title: 'A', data: ['Apple', 'Apricot'] },
  { title: 'B', data: ['Banana'] }
];

<SectionList
  sections={sections}
  renderItem={({ item }) => <Text>{item}</Text>}
  renderSectionHeader={({ section }) => <Text>{section.title}</Text>}
/>

medium

A. No headers will be shown

B. Apple and Banana as headers

C. Only A as header, B is ignored

D. A and B as headers above their items

Solution

1. Step 1: Understand renderSectionHeader usage

   The renderSectionHeader renders the title of each section as header.

2. Step 2: Identify section titles in data

   Sections have titles 'A' and 'B', so these will be shown as headers above their items.

3. Final Answer:

   A and B as headers above their items -> Option D

4. Quick Check:

   Section titles = headers [OK]

Hint: Section headers come from section.title, not items [OK]

Common Mistakes:

• Thinking items become headers
• Assuming only first section shows header
• Forgetting to use renderSectionHeader

4. What is wrong with this SectionList usage?

const sections = [
  { title: 'Numbers', data: 12345 }
];

<SectionList
  sections={sections}
  renderItem={({ item }) => <Text>{item}</Text>}
  renderSectionHeader={({ section }) => <Text>{section.title}</Text>}
/>

medium

A. The title property must be an array

B. The data property should be an array, not a number

C. renderItem should be renderSectionFooter

D. sections should be a flat array, not array of objects

Solution

1. Step 1: Check the type of data property

   The data property must be an array of items, but here it is a number (12345).

2. Step 2: Understand consequences of wrong data type

   This will cause runtime errors because SectionList expects an array to iterate over.

3. Final Answer:

   The data property should be an array, not a number -> Option B

4. Quick Check:

   data must be array [OK]

Hint: data must always be an array, never a single value [OK]

Common Mistakes:

• Passing a single value instead of array to data
• Confusing title type with data type
• Using wrong render method names

5. You want to display a SectionList with sections for weekdays and weekend, but only show days that start with 'S'. How should you prepare the sections data?

hard

A. [{ title: 'Weekdays', data: ['Monday', 'Tuesday', 'Wednesday', 'Thursday', 'Friday', 'Saturday', 'Sunday'] }]

B. [{ title: 'Weekdays', data: ['Monday', 'Tuesday', 'Wednesday', 'Thursday', 'Friday'] }, { title: 'Weekend', data: ['Saturday', 'Sunday'] }]

C. [{ title: 'Weekdays', data: ['Monday', 'Tuesday', 'Wednesday', 'Thursday', 'Friday'].filter(day => day.startsWith('S')) }, { title: 'Weekend', data: ['Saturday', 'Sunday'].filter(day => day.startsWith('S')) }]

D. [{ title: 'Days', data: ['Saturday', 'Sunday'] }]

Solution

1. Step 1: Filter days starting with 'S' in each group

   Use filter(day => day.startsWith('S')) on weekdays and weekend arrays to keep only days starting with 'S'.

2. Step 2: Assign filtered arrays to correct section titles

   Weekdays filtered will be empty, weekend filtered will have 'Saturday' and 'Sunday'. This matches the requirement.

3. Final Answer:

   [{ title: 'Weekdays', data: ['Monday', 'Tuesday', 'Wednesday', 'Thursday', 'Friday'].filter(day => day.startsWith('S')) }, { title: 'Weekend', data: ['Saturday', 'Sunday'].filter(day => day.startsWith('S')) }] -> Option C

4. Quick Check:

   Filter each section's data by startsWith('S') [OK]

Hint: Filter each section's data array before passing to SectionList [OK]

Common Mistakes:

• Not filtering weekdays, showing all days
• Combining all days into one section
• Ignoring filtering and passing raw arrays