React Native React Native 5

Question 1

What does the `keyExtractor` prop in FlatList do?

Accepted Answer

Provides a unique string key for each item to optimize re-rendering

Answer

keyExtractor returns a unique string for each item so React Native can efficiently identify which items changed, added, or removed.

Question 2

Which React Native API would you use to open the device's default email client with a pre-filled address?

Accepted Answer

Linking.openURL('mailto:user@example.com')

Answer

Linking.openURL with a 'mailto:' URI opens the native email client with the specified address pre-filled.

Question 3

How do you create a shadow effect that works on both iOS and Android in React Native?

Accepted Answer

Use shadow* props for iOS and elevation for Android

Answer

iOS uses shadowColor, shadowOffset, shadowOpacity, and shadowRadius, while Android uses the elevation prop to cast a native material shadow.

Question 4

What is the purpose of the `windowSize` prop in FlatList?

Accepted Answer

Determines how many viewport-heights of items to render above and below the visible area

Answer

windowSize defines the number of viewport-sized render windows kept in memory (centered on visible area), balancing memory and scroll performance.

Question 5

Which React Native component would you use to render HTML-style rich text with mixed styles in a single block?

Accepted Answer

Nested Text components with different style props

Answer

Nesting Text components with individual styles inside a parent Text component enables inline mixed styling, similar to HTML spans.

React Native Practice Test