TCS Wings 1 T1 MERN - Set 2

Rahul Vijayan
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TCS Wings 1 T1 MERN - Set 2 

11. Leo is developing a Node.js API and needs to handle large JSON payloads. Which middleware should he add to his Express app?

• a) express.static
• b) express.urlencoded
• c) express.json
• d) body-parser

Answer: c) express.json

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12. Emily is using useState in her React component to handle form data. Which statement correctly updates the state without mutating the existing state object?

• a) setState({ name: 'Emily' })
• b) setState((prevState) => ({ ...prevState, name: 'Emily' }))
• c) setState = { name: 'Emily' }
• d) setState(name: 'Emily')

Answer: b) setState((prevState) => ({ ...prevState, name: 'Emily' }))

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13. Arjun is building a feature to allow users to update their profiles. Which HTTP method should he use for this operation in his Express app?

• a) GET
• b) POST
• c) PUT
• d) DELETE

Answer: c) PUT

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14. Sara is building a component that fetches and displays a user’s profile. She wants the component to refetch data every time the userId prop changes. Which setup should she use in useEffect?

• a) useEffect(() => {}, [])
• b) useEffect(() => { fetchData(); }, [userId])
• c) useEffect(() => { fetchData(); }, [fetchData])
• d) useEffect(fetchData, [userId])

Answer: b) useEffect(() => { fetchData(); }, [userId])

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15. Ben wants to aggregate and group documents in MongoDB by a specific field. Which MongoDB method will help him achieve this?

• a) find
• b) sort
• c) aggregate
• d) mapReduce

Answer: c) aggregate

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16. Emma is designing a React component that updates its style dynamically based on state. Which method is the most React-appropriate way to apply styles conditionally?

• a) Use inline styles with a ternary operator.
• b) Use an if-else statement directly in the JSX.
• c) Use a CSS file with conditional class names.
• d) Write CSS styles in a separate JavaScript function.

Answer: a) Use inline styles with a ternary operator.

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17. Jordan is trying to make his Node.js application scale well. What strategy could he use to handle high traffic efficiently?

• a) Increase the number of GET requests
• b) Use clustering or worker threads to handle multiple requests simultaneously
• c) Increase the memory available to the Node.js application
• d) Rewrite the code in another language

Answer: b) Use clustering or worker threads to handle multiple requests simultaneously

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18. Lisa wants to ensure that her Express app has a global error handler. Which middleware placement will ensure this?

• a) At the beginning of her middleware stack
• b) Just after defining all routes
• c) Inside the router
• d) Inside each route handler

Answer: b) Just after defining all routes

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19. Martin has a React app that interacts with a Node.js backend. He wants to handle failed API requests due to network errors. Which approach should he take?

• a) Log the error to the console
• b) Use a try-catch block with Axios requests
• c) Add retries for each Axios request
• d) Refresh the page after each error

Answer: b) Use a try-catch block with Axios requests

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20. Olivia is designing an Express app with user authentication. Which middleware will help her protect routes from unauthorized access?

• a) Static middleware
• b) Logging middleware
• c) Authentication middleware
• d) Error-handling middleware

Answer: c) Authentication middleware