BetaNXT Interview Questions and Answers

Q1. Explain promises and callback functions with example
Ans. 
Promises and callback functions are used in Node.js for handling asynchronous operations.
• Callback functions are functions passed as arguments to another function to be executed later.

• Promises are objects representing the eventual completion or failure of an asynchronous operation.

• Example of callback function: fs.readFile('file.txt', (err, data) => { if (err) throw err; console.log(data); });

• Example of promise: const re...read more
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Q2. What is middleware
Ans. 
Middleware is a function that has access to the request and response objects in Node.js, and can modify or terminate the request-response cycle.
• Middleware functions can perform tasks like logging, authentication, error handling, etc.

• They are executed sequentially in the order they are defined in the code.

• Example: Express.js uses middleware to handle requests before they reach the route handler.
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Find the second largest elements in an array

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Q1. What is event loop
Ans. 
Event loop is a mechanism in Node.js that allows asynchronous operations to be executed non-blocking.
• Event loop is responsible for handling asynchronous operations in Node.js.

• It allows Node.js to perform non-blocking I/O operations.

• Event loop continuously checks the event queue for new events to execute.

• Event loop helps in efficient handling of multiple concurrent operations in Node.js.
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