What do curly braces in JSX signal?

What do curly braces in JSX signal?

• A. They signal the beginning and end of a JavaScript injection into JSX.
• B. They denote CSS styles.
• C. They are used to create HTML comments.
• D. They identify a component's prop types.

Answer: (A)

Curly braces mark a JavaScript expression inside JSX. They tell React to evaluate whatever is inside and insert the result into the rendered output. This enables dynamic values, calculations, and conditional rendering within your markup—for example, rendering a variable like {userName} or evaluating an expression like {count * 2} or {isReady && <Loader />}. They’re not used for CSS styles, HTML comments, or prop type declarations. For styles, you pass an object to the style prop (e.g., style={{ color: 'red' }}), which itself involves a nested object literal inside the outer JavaScript expression.

Curly braces mark a JavaScript expression inside JSX. They tell React to evaluate whatever is inside and insert the result into the rendered output. This enables dynamic values, calculations, and conditional rendering within your markup—for example, rendering a variable like {userName} or evaluating an expression like {count * 2} or {isReady && }.

They’re not used for CSS styles, HTML comments, or prop type declarations. For styles, you pass an object to the style prop (e.g., style={{ color: 'red' }}), which itself involves a nested object literal inside the outer JavaScript expression.