10+ Enhancesys Innovations Interview Questions and Answers

No, you cannot declare a variable with the same name using var keyword.

• Variables declared with var keyword can only be declared once within the same scope

• Attempting to declare a variable with the same name using var will result in a syntax error

Request and Response objects are created in Node.js using the 'http' module.

• Require the 'http' module in your code

• Use the 'http.createServer()' method to create a server

• Access the request and response objects in the callback function

let, var, and const are all used to declare variables in JavaScript, but they have different scopes and behaviors.

• let: block-scoped variable, can be reassigned

• var: function-scoped variable, can be reassigned

• const: block-scoped variable, cannot be reassigned, but its properties can be modified

Debugging memory leaks involves identifying the source of the leak and fixing it to free up memory.

• Use memory profiling tools like Valgrind or Instruments to detect memory leaks

• Check for unreleased memory allocations in the code

• Look for circular references or retain cycles in object-oriented programming languages

• Use tools like LeakSanitizer in C/C++ programs to detect memory leaks

• Review code for potential memory leaks, such as not freeing allocated memory after use

Callback is a function passed as an argument to another function to be executed later. Async await is a syntax for writing asynchronous code in a synchronous manner.

• Callback is used in event handling, asynchronous programming, and more.

• Async await is a modern way to write asynchronous code in a synchronous style.

• Example: Callback - setTimeout function in JavaScript.

• Example: Async await - fetching data from an API in JavaScript.

EventEmitter is a class in Node.js that allows multiple functions to be attached to an event and triggered when the event is emitted.

• EventEmitter is a core module in Node.js that allows communication between objects in a loosely coupled way.

• It is used for handling events in Node.js applications.

• Listeners can be attached to EventEmitter instances using the 'on' method and events can be emitted using the 'emit' method.

• Example: const EventEmitter = require('events'); const myEmi...read more

Hoisting is a JavaScript behavior where variable and function declarations are moved to the top of their containing scope during the compilation phase.

• Variable and function declarations are hoisted to the top of their scope.

• Only declarations are hoisted, not initializations.

• Function declarations take precedence over variable declarations.

• Example: console.log(x); var x = 5; // Output: undefined

Event loop is a mechanism in programming that allows for asynchronous execution of code.

• Event loop is commonly used in JavaScript to handle asynchronous operations.

• It allows for non-blocking I/O operations by continuously checking the event queue.

• Event loop ensures that the program does not get stuck waiting for a single operation to complete.

Middleware is software that acts as a bridge between different applications or components, allowing them to communicate and work together.

• Middleware facilitates communication between different software components

• It can handle tasks such as data conversion, security, and logging

• Examples include message brokers like RabbitMQ, web servers like Apache Tomcat, and API gateways like Kong