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
111. In React, how are events typically named?
A. In camelCase
B. In kebab-case
C. In snake_case
D. In PascalCase
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Answer: In camelCase
112. What is the primary purpose of handling events in React?
A. To add styles to components
B. To fetch data from APIs
C. To respond to user interactions
D. To define component structure
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Answer: To respond to user interactions
113. In React, which attribute is used to specify an event handler in JSX?
A. event
B. onEvent
C. eventHandler
D. onClick
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Answer: onEvent
114. What is the recommended way to prevent the default behavior of an event in React?
A. By using the event.preventDefault() method
B. By using the e.prevent() method
C. By using the event.preventDefault property
D. By using the event.prevent() property
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Answer: By using the event.preventDefault() method
115. In React, how do you access the value of an input field when handling its onChange event?
A. By using the event.target.value property
B. By using the inputValue property
C. By using the value attribute
D. By using the inputValue attribute
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Answer: By using the event.target.value property
116. Which event handler is used to handle a button click event in React?
A. onSubmit
B. onMouseOver
C. onClick
D. onChange
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Answer: onClick
117. In React, how do you pass arguments to an event handler function when an event occurs?
A. By using the event.arguments property
B. By using the this.arguments property
C. By using arrow functions
D. By using the data- attributes
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Answer: By using arrow functions
118. What is the purpose of using the bind method when defining event handlers in React?
A. To attach event listeners to components
B. To create new components
C. To prevent event propagation
D. To pass arguments to event handlers
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Answer: To pass arguments to event handlers
119. In React, how do you conditionally render different elements based on an event?
A. By using the if-else statement
B. By using the event.switch statement
C. By using the eventHandler function
D. By using JSX conditional rendering
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Answer: By using JSX conditional rendering
120. Which React Hook is commonly used for handling state updates within event handlers in functional components?
A. useState
B. useEffect
C. useEvent
D. useCallback
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Answer: useState
