StyleSheet.create in React Native - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is StyleSheet.create used for in React Native?

StyleSheet.create is used to define styles in React Native in a structured and optimized way. It helps organize style rules and improves performance by creating a stylesheet object.

beginner

How do you define a style with StyleSheet.create?

<p>You pass an object with style names and their properties to <code>StyleSheet.create</code>. For example:<br><code>const styles = StyleSheet.create({ container: { flex: 1, backgroundColor: 'white' } });</code></p>

intermediate

Why is StyleSheet.create better than using plain objects for styles?

It provides validation and better performance by freezing the style objects and sending them only once to native code, reducing overhead.

intermediate

Can you use variables inside StyleSheet.create?

Yes, you can use variables for style values before passing them to StyleSheet.create. This helps keep styles consistent and reusable.

advanced

What happens if you try to modify a style object created by StyleSheet.create at runtime?

The style object is frozen and cannot be changed. This prevents accidental style changes and helps maintain predictable UI.

What does StyleSheet.create return?

A An object with style IDs for native optimization

B A plain JavaScript object without optimization

C A string representing CSS styles

D A function to apply styles

StyleSheet.create returns an object where each style is assigned an ID used internally for better performance.

Which of these is a correct way to define a style using StyleSheet.create?

A const styles = StyleSheet.create(null);

B const styles = StyleSheet.create('text: { fontSize: 16 }');

C const styles = StyleSheet.create([ { fontSize: 16 } ]);

D const styles = StyleSheet.create({ text: { fontSize: 16 } });

The argument must be an object with style names as keys and style properties as values.

Why should you avoid modifying styles created by StyleSheet.create after creation?

A Because styles are frozen and cannot be changed

B Because it causes syntax errors

C Because it slows down the app drastically

D Because styles are strings and immutable

Styles created by StyleSheet.create are frozen to prevent runtime changes.

Which benefit does StyleSheet.create provide over inline styles?

A Automatically converts styles to HTML

B Better performance and style validation

C Allows use of CSS selectors

D Enables dynamic style changes at runtime

It improves performance by sending styles only once to native and validates style properties.

Can you use variables inside the object passed to StyleSheet.create?

A Variables cause errors in styles

B No, only literals are allowed

C Yes, variables can be used for style values

D Only strings can be variables

Variables can be used to keep styles consistent and reusable.

Explain how StyleSheet.create improves performance in React Native apps.

Think about how styles are sent to native code.

Describe the syntax and usage of StyleSheet.create with an example.

Show how to define a container style with background color.