Node.js, often referred to as simply "Node," is a powerful open-source runtime environment that allows developers to execute JavaScript code outside of web browsers. It is designed for building scalable and efficient network applications, particularly on the server side. Node.js leverages a non-blocking, event-driven architecture, making it ideal for handling asynchronous operations and real-time applications. With its vast ecosystem of packages and modules available through npm (Node Package Manager), Node.js has become a popular choice for web development, microservices, APIs, and more, enabling developers to create high-performance applications with ease.
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Practice Test
11. What is the primary role of the Node.js event loop?
A. Handling database queries
B. Managing file I/O operations
C. Executing asynchronous code and managing concurrency
D. Generating HTML templates
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Answer: Executing asynchronous code and managing concurrency
12. In Node.js, what is the core concept that enables non-blocking, asynchronous operations?
A. Callbacks
B. Threads
C. Promises
D. Synchronous execution
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Answer: Callbacks
13. What is the key benefit of non-blocking I/O in Node.js?
A. It makes I/O operations slower but more reliable.
B. It allows multiple threads to run in parallel.
C. It prevents code from executing concurrently.
D. It enables efficient handling of multiple requests without blocking the event loop.
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Answer: It enables efficient handling of multiple requests without blocking the event loop.
14. Which phase of the Node.js event loop processes I/O callbacks?
A. Timers
B. I/O Callbacks
C. Poll
D. Check
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Answer: I/O Callbacks
15. In the Node.js event loop, what happens during the "Timers" phase?
A. File I/O operations are executed.
B. Timers (e.g., setTimeout) are processed, and their associated callbacks are executed.
C. Network operations are performed.
D. Promises are resolved.
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Answer: Timers (e.g., setTimeout) are processed, and their associated callbacks are executed.
16. What is the primary data structure used to store pending events in the Node.js event loop?
A. Linked lists
B. Stacks
C. Queues
D. Arrays
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Answer: Queues
17. Which Node.js method is commonly used to schedule a function to run after a specified number of milliseconds?
A. setInterval
B. setImmediate
C. setTimeout
D. process.nextTick
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Answer: setTimeout
18. What is the purpose of the "Check" phase in the Node.js event loop?
A. To check for syntax errors in the code
B. To perform memory cleanup
C. To execute callbacks scheduled by setImmediate
D. To handle exceptions thrown during I/O operations
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Answer: To execute callbacks scheduled by setImmediate
19. Which Node.js function is used to add a callback to the "next tick queue" for execution in the next iteration of the event loop?
A. setTimeout
B. setImmediate
C. process.nextTick
D. setInterval
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Answer: process.nextTick
20. In Node.js, what is the "Poll" phase responsible for?
A. Executing timer callbacks
B. Handling incoming network requests
C. Cleaning up memory resources
D. Blocking the event loop
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Answer: Handling incoming network requests
