Device info and haptics in React Native - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to import the DeviceInfo module from 'react-native-device-info'.

React Native

import [1] from 'react-native-device-info';

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

ADeviceInfo

BDevice

CInfo

DdeviceInfo

Attempts:

3 left

💡 Hint

Common Mistakes

Using lowercase or partial names like 'deviceInfo' or 'Device'.

Forgetting to import from 'react-native-device-info'.

The correct import is DeviceInfo from the package react-native-device-info.

2fill in blank

medium

Complete the code to get the device's unique ID using DeviceInfo.

React Native

const uniqueId = DeviceInfo.[1]();

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

AgetDeviceName

BgetSystemName

CgetUniqueId

DgetModel

Attempts:

3 left

💡 Hint

Common Mistakes

Using methods like getDeviceName or getModel which return other info.

Forgetting the parentheses to call the function.

The method getUniqueId() returns the unique device ID.

3fill in blank

hard

Fix the error in the code to trigger a light haptic feedback using React Native's Haptics API.

React Native

import { Haptics } from 'react-native';

Haptics.[1]();

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

AimpactLight

BimpactLightAsync

Cimpact

DimpactLightFeedback

Attempts:

3 left

💡 Hint

Common Mistakes

Using a method without 'Async' suffix which does not exist.

Incorrect import or method name casing.

The correct method is impactLightAsync() to trigger light haptic feedback asynchronously.

4fill in blank

hard

Fill both blanks to create a function that vibrates the device for 500 milliseconds using React Native's Vibration API.

React Native

import { Vibration } from 'react-native';

function vibrateDevice() {
  Vibration.[1]([2]);
}

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

Avibrate

BvibrateAsync

C500

D[500]

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'vibrateAsync' which does not exist in React Native core.

Passing duration as an array instead of a number.

The vibrate method is used with a number argument for milliseconds. So Vibration.vibrate(500) vibrates for 500 ms.

5fill in blank

hard

Fill all three blanks to create a dictionary comprehension that maps device info keys to their values only if the value is a non-empty string.

React Native

const deviceInfo = {
  [1]: DeviceInfo.[2](),
  [3]: DeviceInfo.getSystemVersion()
};

const filteredInfo = Object.fromEntries(
  Object.entries(deviceInfo).filter(([key, value]) => value [3] '')
);

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

AdeviceName

BgetDeviceName

C!==

Dmodel

Attempts:

3 left

💡 Hint

Common Mistakes

Using wrong keys or method names.

Using '=' instead of '!=='.

Repeating keys or methods incorrectly.

We map deviceName to getDeviceName() and filter entries where value is not equal to empty string using !==.

Practice

1. Which React Native module provides information about the device's operating system?

easy

A. Platform

B. Dimensions

C. Vibration

D. StatusBar

Solution

1. Step 1: Identify the module for OS info

   The Platform module in React Native gives details about the device OS like 'ios' or 'android'.

2. Step 2: Compare with other modules

   Dimensions gives screen size, Vibration controls haptic feedback, and StatusBar manages the status bar UI, not OS info.

3. Final Answer:

   Platform -> Option A

4. Quick Check:

   OS info = Platform [OK]

Hint: Platform module always gives OS info in React Native [OK]

Common Mistakes:

• Confusing Dimensions with OS info
• Thinking Vibration provides device info
• Assuming StatusBar relates to OS details

2. Which of the following is the correct syntax to get the screen width using React Native's Dimensions module?

easy

A. Dimensions.screen.width()

B. Dimensions.width()

C. Dimensions.get('screen').width

D. Dimensions.getWidth('screen')

Solution

1. Step 1: Recall Dimensions API usage

   The correct method to get screen size is Dimensions.get('screen'), which returns an object with width and height.

2. Step 2: Access width property correctly

   Access the width by .width property, so Dimensions.get('screen').width is correct syntax.

3. Final Answer:

   Dimensions.get('screen').width -> Option C

4. Quick Check:

   Screen width = Dimensions.get('screen').width [OK]

Hint: Use Dimensions.get('screen').width to get screen width [OK]

Common Mistakes:

• Calling width as a function instead of property
• Using wrong method names like getWidth
• Accessing screen as a property instead of argument

3. What will be the result of this React Native code snippet?

import { Vibration } from 'react-native';

Vibration.vibrate(1000);

Choose the correct behavior.

medium

A. The device vibrates for 1 second

B. The device vibrates indefinitely until stopped

C. The device vibrates for 100 milliseconds

D. No vibration occurs because vibrate needs a pattern array

Solution

1. Step 1: Understand Vibration.vibrate parameter

   Passing a number like 1000 to Vibration.vibrate() makes the device vibrate for that many milliseconds (1000 ms = 1 second).

2. Step 2: Check other options

   Indefinite vibration requires a pattern with repeat, 100 ms is too short, and vibrate accepts a number directly, so no pattern array is needed.

3. Final Answer:

   The device vibrates for 1 second -> Option A

4. Quick Check:

   Vibration.vibrate(1000) = 1 second vibration [OK]

Hint: Number argument in vibrate() is vibration duration in ms [OK]

Common Mistakes:

• Thinking vibrate needs a pattern array always
• Confusing milliseconds with seconds
• Assuming vibrate runs indefinitely by default

4. Identify the error in this React Native code snippet that tries to vibrate the device:

import { Vibration } from 'react-native';

Vibration.vibrate([500, 1000]);

medium

A. The vibrate method requires a second argument for repeat

B. The array pattern is correct but missing a repeat flag

C. The array should be passed as a second argument, not the first

D. The vibrate method does not accept an array as argument

Solution

1. Step 1: Check Vibration.vibrate pattern usage

   Vibration.vibrate accepts an array pattern as first argument to define vibration and pause durations.

2. Step 2: Understand repeat flag necessity

   To repeat the pattern, a second boolean argument true is needed. Without it, the pattern runs once, so no error but possibly unintended behavior.

3. Final Answer:

   The array pattern is correct but missing a repeat flag -> Option B

4. Quick Check:

   Pattern array needs repeat flag to loop [OK]

Hint: Add second argument true to repeat vibration pattern [OK]

Common Mistakes:

• Thinking array is invalid argument
• Forgetting second argument for repeat
• Passing array as second argument instead of first

5. You want to create a React Native function that vibrates the device for 500ms, then pauses for 300ms, and repeats this pattern twice. Which code snippet correctly implements this behavior?

hard

A. Vibration.vibrate(500); Vibration.vibrate(300); Vibration.vibrate(500);

B. Vibration.vibrate([500, 300, 500, 300], true); setTimeout(() => Vibration.cancel(), 2600);

C. Vibration.vibrate([500, 300], true); setTimeout(() => Vibration.cancel(), 2600);

D. Vibration.vibrate([500, 300, 500, 300], false);

Solution

1. Step 1: Understand the required pattern

   The pattern is vibrate 500ms, pause 300ms, repeated twice: [500, 300, 500, 300].

2. Step 2: Use repeat false to play exactly twice

   Vibration.vibrate([500, 300, 500, 300], false) executes the sequence once without looping further.

3. Step 3: Eliminate other options

   Using true causes indefinite looping (cancel timing imprecise); shorter pattern loops incorrectly; separate calls lack pauses.

4. Final Answer:

   Vibration.vibrate([500, 300, 500, 300], false); -> Option D

5. Quick Check:

   Two pattern repeats = [500, 300, 500, 300], false [OK]

Hint: Unroll pattern twice with repeat false for exact repeats [OK]

Common Mistakes:

• Using repeat true without precise cancel
• Using false for repeat flag
• Calling vibrate multiple times instead of pattern