Passing parameters between screens in React Native - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is the purpose of passing parameters between screens in React Native?

Passing parameters allows screens to share data, like sending a user's name from a list screen to a detail screen, making the app interactive and dynamic.

beginner

How do you pass parameters when navigating to another screen using React Navigation?

You pass parameters by adding an object as the second argument to the navigation function, for example: navigation.navigate('ScreenName', { paramName: value }).

beginner

How can a screen access the parameters passed to it in React Native with React Navigation?

The screen can access parameters via the route object: route.params.paramName, where route is a prop automatically provided to the screen component.

intermediate

What happens if you try to access a parameter that was not passed to a screen?

Accessing a parameter that was not passed returns undefined, so it is good to provide default values or check if the parameter exists to avoid errors.

beginner

Why is passing parameters between screens important in mobile app development?

It enables screens to communicate and share data, creating a smooth user experience, like showing details of a selected item or passing user input to another screen.

How do you pass a parameter named 'id' with value 5 when navigating to 'Details' screen?

A navigation.goTo('Details', id=5)

B navigation.move('Details', { id: 5 })

C navigation.push('Details', id=5)

D navigation.navigate('Details', { id: 5 })

The correct syntax to pass parameters is navigation.navigate('ScreenName', { paramName: value }).

Where do you find the passed parameters inside the target screen?

A route.params

B props.navigation.params

C navigation.route.params

D props.route.navigation

React Navigation provides the route prop to the screen, and parameters are inside route.params.

What will happen if you try to access a parameter that was not passed?

A It returns undefined

B It returns null

C It throws an error and crashes the app

D It returns an empty string

Accessing a missing parameter returns undefined, so you should handle this case.

Which React Navigation function is commonly used to move to another screen with parameters?

A pop

B goBack

C navigate

D reset

The navigate function is used to go to another screen and can include parameters.

Why should you check if a parameter exists before using it?

A To reduce app size

B To avoid app crashes or unexpected behavior

C To improve app speed

D To change screen colors

Checking parameters prevents errors if the parameter was not passed.

Explain how to pass and access parameters between two screens in React Native using React Navigation.

Think about how you send data when moving from one screen to another and how the receiving screen reads it.

Describe why passing parameters between screens is useful in a mobile app.

Consider how apps show details or personalized info based on user actions.

Practice

1. What is the correct way to pass a parameter named userId with value 42 when navigating to a screen called Profile in React Native?

easy

A. navigation.move('Profile', { userId })

B. navigation.goTo('Profile', userId=42)

C. navigation.push('Profile', userId=42)

D. navigation.navigate('Profile', { userId: 42 })

Solution

1. Step 1: Understand navigation method

   To pass parameters, use navigation.navigate with the screen name and an object of params.

2. Step 2: Check parameter syntax

   The parameter must be inside an object like { userId: 42 } as the second argument.

3. Final Answer:

   navigation.navigate('Profile', { userId: 42 }) -> Option D

4. Quick Check:

   Pass params with navigate(screen, { params }) [OK]

Hint: Use navigate with screen name and params object [OK]

Common Mistakes:

• Using wrong method like goTo or move
• Passing params outside an object
• Forgetting to include params argument

2. Which of the following is the correct syntax to access a parameter named itemId inside a React Native screen component?

easy

A. const itemId = props.navigation.params.itemId;

B. const itemId = navigation.route.params.itemId;

C. const itemId = route.params.itemId;

D. const itemId = params.route.itemId;

Solution

1. Step 1: Identify how params are accessed

   In React Navigation, the screen receives a route prop containing params.

2. Step 2: Use correct property chain

   Access the parameter with route.params.itemId.

3. Final Answer:

   const itemId = route.params.itemId; -> Option C

4. Quick Check:

   Use route.params to get passed parameters [OK]

Hint: Use route.params to access passed data [OK]

Common Mistakes:

• Trying to get params from navigation instead of route
• Incorrect property order like navigation.route.params
• Using props.navigation.params which is invalid

3. Given this code snippet in a React Native app:

navigation.navigate('Details', { productId: 101 });

// In Details screen component:
const Details = ({ route }) => {
  return {route.params.productId};
};

What will be displayed on the screen?

medium

A. productId

B. 101

C. route.params.productId

D. undefined

Solution

1. Step 1: Understand parameter passing

   The productId with value 101 is passed to the Details screen via navigation.navigate.

2. Step 2: Check how parameter is used in Details

   The component accesses route.params.productId and displays it inside a Text component.

3. Final Answer:

   101 -> Option B

4. Quick Check:

   Passed param value is displayed [OK]

Hint: route.params contains passed values to display [OK]

Common Mistakes:

• Expecting param name string instead of value
• Using undefined or wrong property to access param
• Not passing params correctly in navigate

4. What is wrong with this code snippet that tries to pass a parameter name to a screen called Welcome?

navigation.navigate('Welcome', name: 'Alice');

medium

A. Parameters must be passed inside an object as the second argument.

B. The screen name should be lowercase.

C. The parameter name cannot be a string.

D. navigate method does not accept parameters.

Solution

1. Step 1: Check navigate method syntax

   The second argument to navigate must be an object containing parameters.

2. Step 2: Identify error in parameter passing

   The code passes name: 'Alice' without wrapping it in curly braces, which is invalid syntax.

3. Final Answer:

   Parameters must be passed inside an object as the second argument. -> Option A

4. Quick Check:

   Params go inside an object in navigate [OK]

Hint: Always wrap params in an object when navigating [OK]

Common Mistakes:

• Passing params without curly braces
• Using wrong syntax for navigate arguments
• Assuming screen names must be lowercase

5. You want to navigate from a Home screen to a Profile screen and pass both userId and userName. How should you write the navigation call to pass these parameters correctly?

hard

A. navigation.navigate('Profile', { userId: 5, userName: 'John' })

B. navigation.navigate('Profile', userId=5, userName='John')

C. navigation.navigate('Profile', ['userId', 5, 'userName', 'John'])

D. navigation.navigate('Profile', { 'userId': 5 }, { 'userName': 'John' })

Solution

1. Step 1: Understand parameter object structure

   Multiple parameters must be passed inside a single object with key-value pairs.

2. Step 2: Check each option's syntax

   navigation.navigate('Profile', { userId: 5, userName: 'John' }) correctly passes both userId and userName inside one object.

3. Final Answer:

   navigation.navigate('Profile', { userId: 5, userName: 'John' }) -> Option A

4. Quick Check:

   Pass multiple params inside one object [OK]

Hint: Put all params inside one object in navigate call [OK]

Common Mistakes:

• Passing params as separate arguments
• Using array instead of object for params
• Splitting params into multiple objects