Props as read-only data in React - Cheat Sheet & Quick Revision

Recall & Review

beginner

What are props in React?

Props are inputs to React components. They are used to pass data from a parent component to a child component.

beginner

Why should props be treated as read-only in React?

Props should not be changed inside the child component because React relies on props being stable to manage component updates predictably.

intermediate

What happens if you try to modify props directly inside a React component?

Modifying props directly can cause bugs and unexpected behavior because React expects props to be immutable and controlled by the parent component.

intermediate

How can a child component update data passed via props?

A child component can call a function passed as a prop from the parent to request changes. The parent then updates its state and passes new props down.

beginner

Explain the difference between props and state in React.

Props are read-only data passed from parent to child. State is data managed inside a component that can change over time.

In React, can a component modify its own props directly?

A Yes, props can be changed anytime inside the component

B Only if the component is a class component

C No, props are read-only and should not be modified

D Only if the component uses useState hook

Props are read-only data passed from parent to child and should never be modified inside the child component.

How does a child component request a change to data passed via props?

A By directly changing the prop value

B By calling a function passed as a prop from the parent

C By using the useState hook inside the child

D By using the useEffect hook

The child calls a function passed as a prop to notify the parent to update its state, which then updates the props.

What is the main reason React treats props as immutable?

A To keep data flow predictable and components pure

B To improve performance by avoiding unnecessary re-renders

C To allow components to share state

D To enable two-way data binding

Immutable props keep data flow predictable and help React manage component updates reliably.

Which of the following is true about props and state?

A Props are read-only, state can be changed inside the component

B State is passed from parent to child, props are internal

C Props can be changed by the component, state cannot

D Both props and state are read-only

Props are read-only inputs from parent, while state is internal data that a component can change.

If a parent component changes its state, what happens to the props of its child components?

A Props become mutable

B Props remain the same until the child updates them

C Props are deleted and recreated

D Props automatically update to reflect the new state

When the parent state changes, it passes new props to children, causing them to re-render with updated data.

Explain why props in React are considered read-only and how this affects component design.

Think about how data flows in React and why stability matters.

Describe how a child component can update data it receives via props without modifying props directly.

Focus on the communication between parent and child.