React.js, often simply called React, is a highly popular JavaScript library for building user interfaces. Developed and maintained by Facebook, React is renowned for its component-based architecture and the ability to efficiently update and render components when data changes. It is a foundational tool for developing modern web and mobile applications, allowing developers to create dynamic and interactive user interfaces with ease. React's vast ecosystem, including tools like React Native for mobile app development, makes it a top choice for frontend development and a key player in the world of web technologies.
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Practice Test
91. What is React component composition?
A. Combining multiple components
B. Creating new components
C. Styling components
D. Testing components
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Answer: Combining multiple components
92. In React, how can you include one component within another component's JSX?
A. By using the import statement
B. By using the include directive
C. By using the import function
D. By using the compose method
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Answer: By using the import statement
93. What is the primary benefit of component composition in React?
A. Reusability of components
B. Improved performance
C. Tighter security
D. Simpler component structure
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Answer: Reusability of components
94. In React, what is a higher-order component (HOC)?
A. A component that is placed higher in the component tree
B. A component that returns another component
C. A component that has a higher specificity
D. A component with higher rendering performance
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Answer: A component that returns another component
95. How do you pass data from a parent component to a child component in React?
A. By using props
B. By using state
C. By using context
D. By using the return statement
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Answer: By using props
96. In React, what is the purpose of the children prop?
A. To define child components
B. To pass data from parent to child
C. To access child components
D. To render child elements
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Answer: To render child elements
97. What is the recommended way to control the rendering of child components in React?
A. By using conditional rendering
B. By using the this.renderChild method
C. By using the render prop
D. By using the renderChild prop
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Answer: By using conditional rendering
98. Which React concept allows you to create reusable UI elements that accept their structure as props?
A. Functional components
B. JSX elements
C. Higher-order components (HOCs)
D. Render props
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Answer: Higher-order components (HOCs)
99. In React, what is the purpose of the key prop when rendering a list of components?
A. To specify the list item's content
B. To define a unique identifier
C. To style the list items
D. To control the list's state
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Answer: To define a unique identifier
100. How can you conditionally render one component or another in React based on a condition?
A. By using the if-else statement
B. By using the switch statement
C. By using the map function
D. By using conditional rendering in JSX
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Answer: By using conditional rendering in JSX
