Default props in React Native - Cheat Sheet & Quick Revision

Recall & Review

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What are default props in React Native?

Default props are values given to a component's props that are used if no value is provided by the parent component. They ensure the component works with sensible defaults.

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How do you define default props in a functional React Native component?

You can define default props by assigning a default value in the function parameter or by setting the component's defaultProps property.

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Why are default props useful in mobile app components?

They prevent errors by providing fallback values, making components more robust and easier to reuse without always specifying every prop.

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Example: What will be the output if a component has a default prop color='blue' but is used without specifying color?

The component will use the default color 'blue' and render accordingly, even if the parent does not provide a color prop.

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Can default props be overridden? How?

Yes, default props are overridden by passing a prop with the same name from the parent component. The passed value takes priority.

What happens if a React Native component is rendered without a prop that has a default value?

A The component ignores the missing prop.

B The component crashes.

C The prop value is undefined.

D The component uses the default prop value.

If a prop is missing, React Native uses the default prop value to keep the component working smoothly.

How can you set default props for a functional component in React Native?

A By assigning default values in the function parameters or using <code>Component.defaultProps</code>.

B By using <code>this.setDefaultProps()</code>.

C By wrapping the component in a <code>DefaultProps</code> tag.

D By importing default props from a library.

Default props can be set by default parameters or by assigning to Component.defaultProps.

If a parent component passes a prop value, what happens to the default prop?

A An error occurs.

B The passed prop value overrides the default prop.

C Both values are merged.

D The default prop overrides the passed value.

Passed props always override default props to allow customization.

Why should you use default props in your components?

A To provide fallback values and avoid errors when props are missing.

B To make components slower.

C To force users to always pass props.

D To disable props.

Default props help components work safely even if some props are not provided.

Which of these is a correct way to define default props for a React Native functional component named Button?

A Button.setDefaultProps({ color: 'red' });

B defaultProps(Button) = { color: 'red' };

C Button.defaultProps = { color: 'red' };

D Button.props.default = { color: 'red' };

The correct syntax is to assign an object to Button.defaultProps.

Explain what default props are and why they are helpful in React Native components.

Think about what happens if a prop is missing when a component is used.

Describe two ways to set default props in a React Native functional component.

One way is inside the function signature, the other is a static property on the component.