Passing props to components in React - Step-by-Step Execution

Concept Flow - Passing props to components

Parent Component

↓

Define props values

↓

Render Child Component with props

↓

Child Component receives props

↓

Child uses props to render output

The parent component defines values and passes them as props to the child component, which then uses these props to display content.

Execution Sample

React

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

function App() {
  return <Greeting name="Alice" />;
}

This code passes the name 'Alice' as a prop to the Greeting component, which displays a personalized message.

Execution Table

Step	Action	Props Passed	Child Output
1	App renders Greeting	name: 'Alice'	Hello, Alice!
2	Greeting receives props	name: 'Alice'	Hello, Alice!
3	Greeting returns JSX	name: 'Alice'	<h1>Hello, Alice!</h1>
4	React renders output to DOM	name: 'Alice'	Visible: Hello, Alice!

💡 Rendering completes after Greeting returns JSX and React updates the DOM.

Variable Tracker

Variable	Start	After Step 1	After Step 2	Final
props.name	undefined	Alice	Alice	Alice

Key Moments - 2 Insights

Why does Greeting receive props with the name 'Alice'?

Because in step 1, App passes the prop name='Alice' when rendering Greeting, as shown in the execution_table row 1.

What happens if we don't pass a prop to Greeting?

Greeting.props.name would be undefined, so the output would show 'Hello, !' as no name is provided, similar to the initial 'Start' state in variable_tracker.

Visual Quiz - 3 Questions

Look at the execution_table at step 2, what is the value of props.name inside Greeting?

A "Alice"

B undefined

C null

D "Greeting"

💡 Hint

Check the 'Props Passed' column at step 2 in the execution_table.

At which step does React update the DOM with the greeting message?

A Step 1

B Step 4

C Step 3

D Step 2

💡 Hint

Look for the step where the output becomes visible in the execution_table.

If App passed name="Bob" instead of "Alice", what would props.name be at step 2?

A undefined

B "Alice"

C "Bob"

D null

💡 Hint

Refer to how props are passed from App to Greeting in the execution_table step 1.

Concept Snapshot

Passing props to components:
- Parent sends data as props: <Child propName="value" />
- Child receives props as function argument
- Use props inside child: props.propName
- Props are read-only inside child
- Enables reusable, dynamic components

Full Transcript

In React, components can receive data from their parent components through props. The parent component includes the child component in its JSX and passes values as attributes. These values become properties (props) accessible inside the child component as an object. The child uses these props to render dynamic content. For example, a Greeting component can receive a name prop and display a personalized message. The execution flow starts with the parent rendering the child with props, the child receiving and using the props, and finally React rendering the output to the screen. Props are immutable inside the child, meaning the child should not change them. This pattern helps build reusable and flexible components.