React Native React Native 2

Question 1

Which React Native component is used to handle keyboard input and keep the focused field visible?

Accepted Answer

KeyboardAvoidingView

Answer

KeyboardAvoidingView automatically adjusts its height or padding when the software keyboard appears so the focused input remains visible.

Question 2

What is the purpose of the `useNativeDriver: true` option in Animated API calls?

Accepted Answer

Runs animations on the native thread instead of the JS thread

Answer

useNativeDriver: true offloads animation execution to the native thread, preventing JS thread jank and producing smoother animations.

Question 3

Which Metro bundler flag lets you start the packager on a custom port?

Accepted Answer

--port

Answer

Running `npx react-native start --port 8082` starts Metro on a non-default port.

Question 4

In React Native, what does the `onLayout` prop provide to its callback?

Accepted Answer

An event with the component's x, y, width, and height measurements

Answer

The onLayout callback receives a nativeEvent containing layout data: x, y, width, and height of the component.

Question 5

Which API would you use to detect whether the device is currently online or offline in React Native?

Accepted Answer

NetInfo from @react-native-community/netinfo

Answer

The @react-native-community/netinfo library exposes NetInfo, which provides the network connection state and type.

React Native Practice Test