Xcelore Senior Software Engineer Interview Questions, Process, and Tips for Experienced

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

• 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.

• Hoisting can lead to unexpected behavior if not understood properly.

Closures are functions that have access to variables from their containing scope even after the parent function has finished executing.

• Closures allow functions to maintain access to variables from their outer scope

• They are created when a function is defined within another function

• Closures are commonly used in event handlers and callbacks

Promises are a way to handle asynchronous operations in JavaScript, providing a cleaner alternative to callbacks.

• Promises represent the eventual completion (or failure) of an asynchronous operation.

• They allow you to chain multiple asynchronous operations together.

• Promises have states: pending, fulfilled, or rejected.

• You can handle the result of a promise using .then() and .catch() methods.

• Example: const myPromise = new

Callback Hell is a situation in asynchronous programming where multiple nested callbacks make the code hard to read and maintain.

• Occurs when multiple asynchronous operations are nested within each other

• Leads to deeply nested code which is hard to read and maintain

• Can be avoided by using Promises or async/await syntax

Async/Await is a feature in JavaScript that allows for asynchronous programming using promises.

• Async/Await is syntactic sugar built on top of promises in JavaScript.

• It allows for writing asynchronous code that looks synchronous, making it easier to read and maintain.

• Async functions return a promise, which allows for chaining multiple asynchronous operations.

• Await keyword is used inside async functions to wait for a pro...read more

A simple Todo List app built using React

• Create a new React project using create-react-app

• Create a Todo component to display the list of todos

• Use state to manage the list of todos and input field for adding new todos

• Implement functionality to add, delete, and mark todos as completed

REST API is a standard protocol for web services using HTTP, while GraphQL is a query language for APIs.

• REST API follows a client-server architecture with stateless communication, while GraphQL allows clients to request only the data they need.

• REST API typically uses multiple endpoints for different resources, while GraphQL uses a single endpoint for flexible data retrieval.

• REST API has predefined data structures, whil...read more