LayoutAnimation in React Native - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ ui_behavior

intermediate

What happens when LayoutAnimation.configureNext is called before state change?

Consider a React Native component that toggles a box's height on button press.
What is the visible effect if LayoutAnimation.configureNext(LayoutAnimation.Presets.easeInEaseOut) is called just before updating the height state?

React Native

import React, {useState} from 'react';
import {View, Button, LayoutAnimation} from 'react-native';

export default function App() {
  const [expanded, setExpanded] = useState(false);

  const toggle = () => {
    LayoutAnimation.configureNext(LayoutAnimation.Presets.easeInEaseOut);
    setExpanded(!expanded);
  };

  return (
    <View>
      <Button title="Toggle" onPress={toggle} />
      <View style={{height: expanded ? 200 : 50, backgroundColor: 'skyblue'}} />
    </View>
  );
}

A The box fades out instead of resizing.

B The box instantly changes height without animation.

C The box smoothly animates its height change between 50 and 200 pixels.

D The app crashes due to incorrect LayoutAnimation usage.

💡 Hint

LayoutAnimation.configureNext triggers animation for the next layout change.

Calling LayoutAnimation.configureNext before a state change causes the layout change to animate smoothly using the specified preset.

❓ lifecycle

intermediate

When should LayoutAnimation.configureNext be called in a component?

In React Native, to animate layout changes triggered by state updates, when is the best time to call LayoutAnimation.configureNext?

A Inside the render method after returning JSX.

B Immediately before the state update that causes the layout change.

C Inside useEffect with an empty dependency array.

D After the layout change has completed.

💡 Hint

Think about when the layout change is triggered.

LayoutAnimation.configureNext must be called before the state update that triggers the layout change to animate it properly.

📝 Syntax

advanced

Identify the correct way to enable LayoutAnimation on Android

By default, LayoutAnimation is disabled on Android. Which code snippet correctly enables it?

A

import { UIManager, Platform } from 'react-native';
if (Platform.OS === 'android') {
  UIManager.setLayoutAnimationEnabledExperimental(true);
}

B

import { UIManager } from 'react-native';
UIManager.enableLayoutAnimation(true);

C

import { LayoutAnimation } from 'react-native';
LayoutAnimation.enableAndroid(true);

D

import { Platform } from 'react-native';
if (Platform.OS === 'android') {
  LayoutAnimation.setEnabled(true);
}

💡 Hint

Check the official React Native docs for Android setup.

On Android, you must call UIManager.setLayoutAnimationEnabledExperimental(true) to enable LayoutAnimation.

🔧 Debug

advanced

Why does LayoutAnimation not animate on a state change?

A developer calls LayoutAnimation.configureNext before a state update, but the UI changes instantly without animation. What is a likely cause?

A The component is wrapped in a ScrollView which disables animations.

B The state update is asynchronous and LayoutAnimation.configureNext must be called inside a callback.

C LayoutAnimation.configureNext must be called after the state update, not before.

D The component uses a style property that LayoutAnimation does not support, like 'backgroundColor'.

💡 Hint

LayoutAnimation only animates layout properties like size and position.

LayoutAnimation only animates layout-related style changes such as height, width, margin, and position. It does not animate color changes.

🧠 Conceptual

expert

What is the effect of using LayoutAnimation with a custom config that has duration 0?

If you configure LayoutAnimation with a custom config where the duration is set to 0 milliseconds, what will be the visible effect on the UI when a layout change occurs?

React Native

const config = {
  duration: 0,
  update: {
    type: LayoutAnimation.Types.easeInEaseOut,
    property: LayoutAnimation.Properties.opacity
  }
};
LayoutAnimation.configureNext(config);

A The layout change happens instantly with no visible animation.

B The layout change animates slowly despite duration 0.

C The app throws a runtime error due to invalid duration.

D The layout change animates with default duration ignoring 0.

💡 Hint

Think about what a zero duration means for animation timing.

A duration of 0 means the animation completes immediately, so the layout change appears instant with no animation.