10+ Jawaharlal Nehru Centre for Advanced Scientific Research Interview Questions and Answers

Indexes in MongoDB improve query performance by allowing the database to quickly locate and retrieve specific documents.

• Indexes help to speed up query performance by allowing the database to quickly locate specific documents based on the indexed fields.

• Without indexes, MongoDB would have to perform a collection scan, which can be slow and resource-intensive.

• Indexes can be created on single fields or compound fields to further optimize query performance.

• However, indexes come w...read more

Modules in Node.js are reusable blocks of code that encapsulate related functionality.

• Modules in Node.js can be built-in modules like fs (file system) or third-party modules like express.

• Modules help in organizing code into separate files for better maintainability and reusability.

• Modules can be imported using the require() function in Node.js.

The JAVA API is a collection of pre-written classes and interfaces that provide ready-to-use functionality for Java developers.

• The JAVA API allows developers to save time and effort by using pre-built code for common tasks.

• It provides a wide range of classes and interfaces for various purposes such as file handling, networking, database connectivity, GUI development, etc.

• Developers can leverage the API to access system resources, interact with external services, and perform c...read more

Inheritance allows a class to inherit properties and behaviors from another class. Abstract classes cannot be instantiated and can have abstract methods. Interfaces define a contract for classes to implement.

• Inheritance allows a class to inherit properties and behaviors from another class

• Abstract classes cannot be instantiated and can have abstract methods

• Interfaces define a contract for classes to implement

Yes, let and const variables are hoisted but not initialized.

• let and const variables are hoisted to the top of their block scope, but they are not initialized until the actual line of code is executed.

• This means that you cannot access a let or const variable before it is declared in the code.

• For example, trying to access a let variable before it is declared will result in a ReferenceError.

Mongoose is an Object Data Modeling (ODM) library for MongoDB that provides a higher level of abstraction and simplifies interactions with the database.

• Mongoose provides schema validation which helps maintain data integrity.

• Mongoose simplifies querying and data manipulation with built-in functions.

• Mongoose supports middleware functions for pre and post processing of data operations.

Hooks are a feature in React that allow you to use state and other React features in functional components. useRef is a hook that allows you to create a mutable object that persists for the lifetime of the component.

• Hooks are used to add state and lifecycle methods to functional components in React

• useRef is used to create a mutable reference that persists between renders

• useRef can be used to access DOM elements directly in functional components

ES6 introduced several new features and improvements to JavaScript, making it more powerful and efficient.

• Arrow functions for more concise syntax

• Let and const for block-scoped variables

• Classes for easier object-oriented programming

• Template literals for easier string interpolation

• Default parameters and rest parameters for function arguments

• Destructuring assignment for easier data extraction

• Promises for asynchronous programming

• Modules for better code organization

Global context refers to the overall environment or setting in which something exists or operates.

• Global context encompasses all variables, functions, and objects that are accessible throughout an entire program.

• It can be thought of as the 'big picture' view of a program's execution.

• In web development, global context includes the window object in JavaScript.

Temporal dead zone is a period during the variable creation process where accessing the variable results in a ReferenceError.

• Occurs when trying to access a variable before it has been declared with let or const

• Happens due to the variable being in the temporal dead zone until it is declared

• Example: accessing a variable before its declaration will result in a ReferenceError