Passing props to components in React - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to pass a prop named title with value "Hello" to the Header component.

React

function App() {
  return <Header [1] />;
}

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

Atitle="Hello"

Btext="Hello"

Cname="Hello"

Dcontent="Hello"

Attempts:

3 left

💡 Hint

Common Mistakes

Using a wrong prop name like 'text' or 'name' instead of 'title'.

Forgetting to add quotes around the string value.

The prop name must match the expected prop in the component. Here, title is the correct prop name.

2fill in blank

medium

Complete the code to access the message prop inside the Greeting component.

React

function Greeting(props) {
  return <p>{props.[1]</p>;
}

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

Acontent

Btext

Cmessage

Dtitle

Attempts:

3 left

💡 Hint

Common Mistakes

Using a different prop name than what was passed.

Trying to access props without the props. prefix.

Props are accessed via props.propName. Here, the prop is named message.

3fill in blank

hard

Fix the error in the code by completing the destructuring of props in the Info component.

React

function Info([1]) {
  return <div>{name} is {age} years old.</div>;
}

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

Aprops

B{name, age}

Cname, age

Dinfo

Attempts:

3 left

💡 Hint

Common Mistakes

Not using curly braces for destructuring.

Using a single variable name instead of destructuring.

Destructuring props requires curly braces around the prop names inside the function parameter.

4fill in blank

hard

Fill both blanks to pass color and size props to the Button component.

React

function App() {
  return <Button [1] [2] />;
}

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

Acolor="blue"

Bsize="large"

Cstyle="blue"

Dfont="large"

Attempts:

3 left

💡 Hint

Common Mistakes

Using incorrect prop names like 'style' or 'font'.

Forgetting to add quotes around string values.

Props are passed as attributes with their names and values. Here, color and size are the correct prop names.

5fill in blank

hard

Fill all three blanks to create a UserCard component that receives name and email props and displays them.

React

function UserCard([1], [2]) {
  return (
    <div>
      <h2>[3]</h2>
      <p>{email}</p>
    </div>
  );
}

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

Aname

Bemail

Duser

Attempts:

3 left

💡 Hint

Common Mistakes

Not destructuring both props correctly.

Using a wrong variable name inside JSX.

The component destructures name and email props. Then it displays name inside the h2 tag.

Practice

1. What is the main purpose of props in React components?

easy

A. To handle user events like clicks

B. To store local state inside a component

C. To pass data from a parent component to a child component

D. To style components with CSS

Solution

1. Step 1: Understand the role of props

   Props are used to send data from one component to another, specifically from parent to child.

2. Step 2: Differentiate props from other React features

   State stores local data, events handle interactions, and CSS styles components, but props specifically pass data down.

3. Final Answer:

   To pass data from a parent component to a child component -> Option C

4. Quick Check:

   Props = data passing [OK]

Hint: Props always send data down from parent to child [OK]

Common Mistakes:

• Confusing props with state
• Thinking props handle events
• Believing props style components

2. Which of the following is the correct way to pass a prop named title with value "Hello" to a component Header?

easy

A.

B.

C.

D.

Solution

1. Step 1: Recall JSX prop syntax

   Props are passed like HTML attributes: name="value" or name={expression}.

2. Step 2: Check each option

   uses correct string syntax.

   misses quotes around string.

   uses invalid quotes.

   uses colon which is invalid in JSX.

3. Final Answer:

   <Header title="Hello" /> -> Option B

4. Quick Check:

   Props look like HTML attributes [OK]

Hint: Use quotes for string props in JSX [OK]

Common Mistakes:

• Omitting quotes for string values
• Using colons instead of equals
• Adding extra quotes around prop names

3. What will be rendered by this React component?

function Greeting(props) {
  return <h1>Hello, {props.name}!</h1>;
}

// Usage:
<Greeting name="Alice" />

medium

A. Hello, Alice!

B. Hello, {props.name}!

C. Hello, name!

D. Error: props is undefined

Solution

1. Step 1: Understand how props are used inside the component

   The component receives props and accesses props.name to display the name.

2. Step 2: Check the usage of the component

   The component is called with name="Alice", so props.name is "Alice".

3. Final Answer:

   <h1>Hello, Alice!</h1> -> Option A

4. Quick Check:

   props.name = Alice [OK]

Hint: Props values replace placeholders inside JSX [OK]

Common Mistakes:

• Printing literal {props.name} instead of value
• Forgetting to pass the prop
• Assuming props is undefined

4. Identify the error in this code snippet:

function Welcome(props) {
  return <h2>Welcome, {props.user}!</h2>;
}

// Usage:
<Welcome user=John />

medium

A. Missing quotes around string prop value 'John'

B. Props object is not passed correctly

C. Component name should be lowercase

D. JSX tags are not closed properly

Solution

1. Step 1: Check the prop usage in JSX

   In JSX, string prop values must be quoted, e.g., user="John".

2. Step 2: Identify the error in usage

   The code uses user=John without quotes, causing a syntax error.

3. Final Answer:

   Missing quotes around string prop value 'John' -> Option A

4. Quick Check:

   String props need quotes [OK]

Hint: Always quote string props in JSX [OK]

Common Mistakes:

• Omitting quotes for string props
• Using lowercase component names
• Leaving JSX tags unclosed

5. Given this parent and child component code, what will be the output?

function Child({ message }) {
  return <p>Message: {message || 'No message'}</p>;
}

function Parent() {
  const msg = '';
  return <Child message={msg} />;
}

hard

A. Message:

B. Error: message prop missing

C. Message: undefined

D. Message: No message

Solution

1. Step 1: Analyze the prop value passed

   The parent passes msg which is an empty string '' as the message prop.

2. Step 2: Understand the child component's rendering logic

   The child uses {message || 'No message'}. Since empty string is falsy, it falls back to 'No message'.

3. Final Answer:

   <p>Message: No message</p> -> Option D

4. Quick Check:

   Falsy empty string triggers fallback [OK]

Hint: Falsy props like '' use fallback values in JSX [OK]

Common Mistakes:

• Assuming empty string is truthy
• Expecting empty string to display as is
• Thinking missing prop causes error here